power_lowlevel.h File Reference

#include "power.h"

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Functions
void	power_lowlevel_init ()
void	power_usage_inverter (t_power_usage *power_usage, float in_dens, float in_prob, float size, float period)
void	power_usage_inverter_irregular (t_power_usage *power_usage, float *dyn_power_input, float in_density, float in_probability, float PMOS_size, float NMOS_size, float period)
void	power_usage_wire (t_power_usage *power_usage, float capacitance, float density, float period)
void	power_usage_mux_singlelevel_static (t_power_usage *power_usage, float *out_prob, float *out_dens, float *V_out, int num_inputs, int selected_idx, float *in_prob, float *in_dens, float *v_in, float transistor_size, boolean v_out_restored, float period)
void	power_usage_MUX2_transmission (t_power_usage *power_usage, float size, float *in_dens, float *in_prob, float sel_dens, float out_dens, float period)
void	power_usage_mux_singlelevel_dynamic (t_power_usage *power_usage, int num_inputs, float out_density, float v_out, float *in_prob, float *in_density, float *v_in, float sel_dens, float sel_prob, float transistor_size, float period)
void	power_usage_level_restorer (t_power_usage *power_usage, float *dyn_power_in, float in_density, float in_probability, float period)
float	power_calc_pb_switching_from_c_internal (t_pb *pb, t_pb_graph_node *pb_graph_node)
float	power_calc_mux_v_out (int num_inputs, float transistor_size, float v_in, float in_prob_avg)
float	power_calc_node_switching (float capacitance, float density, float period)
float	power_calc_buffer_size_from_Cout (float C_out)

Function Documentation

float power_calc_buffer_size_from_Cout

(

float

C_out

)

This function calculates the short-circuit factor for a buffer. This factor represents the short-circuit power of a buffer, as a factor of switching power.

• stages: Number of stages of the buffer
• gain: The gain at each stage
• level_restorer: Whether this buffer must level-restore the input to Vdd
• input_mux_size: For level-restoring buffers, what is the size of the mux driving it

Definition at line 852 of file power_lowlevel.c.

                                                    {
    int i;
    float C_found;

    t_transistor_inf * nmos_info = &g_power_tech->NMOS_inf;
    t_transistor_inf * pmos_info = &g_power_tech->PMOS_inf;

    assert(nmos_info->num_size_entries == pmos_info->num_size_entries);

    for (i = 0; i < nmos_info->num_size_entries; i++) {
        C_found = nmos_info->size_inf[i].C_d + pmos_info->size_inf[i].C_d;

        /* Not likely, since floating point */
        if (C_out == C_found) {
            return nmos_info->size_inf[i].size;
        }

        /* Gone past */
        if (C_found > C_out) {
            if (i == 0) {
                power_log_msg(POWER_LOG_WARNING,
                        "Attempted to search for a transistor with a capacitance smaller than the smallest in the technology file.\n");
                return nmos_info->size_inf[i].size;
            } else {
                float C_prev = nmos_info->size_inf[i - 1].C_d
                        + pmos_info->size_inf[i - 1].C_d;
                float percent_upper = (C_out - C_prev) / (C_found - C_prev);
                return percent_upper * nmos_info->size_inf[i].size
                        + (1 - percent_upper) * nmos_info->size_inf[i - 1].size;
            }
        }

        /* Reached the End */
        if (i == nmos_info->num_size_entries - 1) {
            power_log_msg(POWER_LOG_WARNING,
                    "Attempted to search for a transistor with a capacitance greater than the largest in the technology file.\n");
            return nmos_info->size_inf[i].size;
        }
    }

    return 0;
}

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float power_calc_mux_v_out	(	int	num_inputs,
		float	transistor_size,
		float	v_in,
		float	in_prob_avg
	)

This function calcualtes the output voltage of a single-level multiplexer

• num_inputs: Number of inputs of the multiplexer
• transistor_size: The size of the NMOS transistors (must be 1.0)
• v_in: The input voltage of the selcted input
• in_prob_avg: The average signal probabilities of the non-selected inputs

Definition at line 583 of file power_lowlevel.c.

                           {
    t_power_mux_volt_inf * mux_volt_inf_low;
    t_power_mux_volt_inf * mux_volt_inf_high;
    t_power_mux_volt_pair * lower;
    t_power_mux_volt_pair * upper;
    float v_out_min, v_out_max;
    float v_out_low;
    float v_out_high;
    bool over_range = false;

    assert(transistor_size >= 1.0);

    t_power_nmos_mux_inf * mux_nmos_inf_lower = NULL;
    t_power_nmos_mux_inf * mux_nmos_inf_upper = NULL;

// Check if nmos size is beyond range
    if (transistor_size
            >= g_power_tech->nmos_mux_info[g_power_tech->num_nmos_mux_info - 1].nmos_size) {
        mux_nmos_inf_lower =
                &g_power_tech->nmos_mux_info[g_power_tech->num_nmos_mux_info - 1];
        over_range = true;
    } else {
        for (int i = 1; i < g_power_tech->num_nmos_mux_info; i++) {
            if (transistor_size < g_power_tech->nmos_mux_info[i].nmos_size) {
                mux_nmos_inf_lower = &g_power_tech->nmos_mux_info[i - 1];
                mux_nmos_inf_upper = &g_power_tech->nmos_mux_info[i];
                break;
            }
        }
    }

    if (transistor_size
            > g_power_tech->nmos_mux_info[g_power_tech->num_nmos_mux_info - 1].nmos_size) {
        power_log_msg(POWER_LOG_ERROR,
                "The architectures uses multiplexers with \
                transistors sizes larger than what is defined in the <multiplexers> \
                section of the technology file.");
    }

    if (num_inputs > mux_nmos_inf_lower->max_mux_sl_size
            || (!over_range && num_inputs > mux_nmos_inf_upper->max_mux_sl_size)) {
        power_log_msg(POWER_LOG_ERROR,
                "The circuit contains a single-level mux larger than \
                what is defined in the <multiplexers> section of the \
                technology file.");
    }

    mux_volt_inf_low = &mux_nmos_inf_lower->mux_voltage_inf[num_inputs];

    power_find_mux_volt_inf(&lower, &upper, mux_volt_inf_low, v_in);
    if (lower->v_in == v_in || !upper) {
        v_out_min = lower->v_out_min;
        v_out_max = lower->v_out_max;
    } else {
        float perc_upper = (v_in - lower->v_in) / (upper->v_in - lower->v_in);
        v_out_min = (1 - perc_upper) * lower->v_out_min
                + perc_upper * upper->v_out_min;
        v_out_max = (1 - perc_upper) * lower->v_out_max
                + perc_upper * upper->v_out_max;
    }
    v_out_low = in_prob_avg * v_out_max + (1 - in_prob_avg) * v_out_min;

    if (!over_range) {
        mux_volt_inf_high = &mux_nmos_inf_upper->mux_voltage_inf[num_inputs];
        power_find_mux_volt_inf(&lower, &upper, mux_volt_inf_high, v_in);
        if (lower->v_in == v_in || !upper) {
            v_out_min = lower->v_out_min;
            v_out_max = lower->v_out_max;
        } else {
            float perc_upper = (v_in - lower->v_in)
                    / (upper->v_in - lower->v_in);
            v_out_min = (1 - perc_upper) * lower->v_out_min
                    + perc_upper * upper->v_out_min;
            v_out_max = (1 - perc_upper) * lower->v_out_max
                    + perc_upper * upper->v_out_max;
        }
        v_out_high = in_prob_avg * v_out_max + (1 - in_prob_avg) * v_out_min;
    }

    if (over_range) {
        return v_out_low;
    } else {
        float perc_upper =
                (transistor_size - mux_nmos_inf_lower->nmos_size)
                        / (mux_nmos_inf_upper->nmos_size
                                - mux_nmos_inf_lower->nmos_size);
        return v_out_high * perc_upper + (1 - perc_upper) * v_out_low;
    }
}

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float power_calc_node_switching	(	float	capacitance,
		float	density,
		float	period
	)

Calculates the switching power of a node

• capacitance: The capacitance of the nodoe
• density: The transition density of the node

Definition at line 86 of file power_lowlevel.c.

                      {
    return 0.5 * g_power_tech->Vdd * g_power_tech->Vdd * capacitance * density
            / period;
}

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float power_calc_pb_switching_from_c_internal	(	t_pb *	pb,
		t_pb_graph_node *	pb_graph_node
	)

void power_lowlevel_init

(

)

This file provides functions that calculate the power of low-level components (inverters, simple multiplexers, etc)

Initializer function for this module, called by power_init

Definition at line 47 of file power_lowlevel.c.

                           {
    float C_d, C_s, C_g;

    power_calc_transistor_capacitance(&C_d, &C_s, &C_g, NMOS, 1.0);
    g_power_commonly_used->NMOS_1X_C_d = C_d;
    g_power_commonly_used->NMOS_1X_C_g = C_g;
    g_power_commonly_used->NMOS_1X_C_s = C_s;

    power_calc_transistor_capacitance(&C_d, &C_s, &C_g, PMOS,
            g_power_tech->PN_ratio);
    g_power_commonly_used->PMOS_1X_C_d = C_d;
    g_power_commonly_used->PMOS_1X_C_g = C_g;
    g_power_commonly_used->PMOS_1X_C_s = C_s;

    g_power_commonly_used->NMOS_1X_st_leakage = power_calc_leakage_st(NMOS,
            1.0);
    g_power_commonly_used->PMOS_1X_st_leakage = power_calc_leakage_st(PMOS,
            1.0 * g_power_tech->PN_ratio);

    g_power_commonly_used->INV_1X_C_in = g_power_commonly_used->NMOS_1X_C_g
            + g_power_commonly_used->PMOS_1X_C_g;
    g_power_commonly_used->INV_1X_C = g_power_commonly_used->NMOS_1X_C_g
            + g_power_commonly_used->PMOS_1X_C_g
            + g_power_commonly_used->NMOS_1X_C_d
            + g_power_commonly_used->PMOS_1X_C_d;

    power_calc_transistor_capacitance(&C_d, &C_s, &C_g, NMOS, 2.0);
    g_power_commonly_used->INV_2X_C = C_g + C_d;
    power_calc_transistor_capacitance(&C_d, &C_s, &C_g, PMOS,
            2.0 * g_power_tech->PN_ratio);
    g_power_commonly_used->INV_2X_C += C_g + C_d;

}

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void power_usage_inverter	(	t_power_usage *	power_usage,
		float	in_dens,
		float	in_prob,
		float	size,
		float	period
	)

Calculates the power of an inverter

• power_usage: (Return value) The power usage of the inverter
• in_dens: The transition density of the input
• in_prob: The signal probability of the input
• size: The inverter size, relative to a min-size inverter

Definition at line 110 of file power_lowlevel.c.

                                                 {
    float C_drain, C_gate, C_source;
    float C_inv;

    float PMOS_size = g_power_tech->PN_ratio * size;
    float NMOS_size = size;

    power_usage->dynamic = 0.;
    power_usage->leakage = 0.;

    C_inv = 0.;

    power_calc_transistor_capacitance(&C_drain, &C_source, &C_gate, NMOS,
            NMOS_size);
    C_inv += C_gate + C_drain;

    power_calc_transistor_capacitance(&C_drain, &C_source, &C_gate, PMOS,
            PMOS_size);
    C_inv += C_gate + C_drain;

    power_usage->dynamic = power_calc_node_switching(C_inv, in_dens, period);

    power_usage->leakage = in_prob * power_calc_leakage_st(PMOS, PMOS_size)
            + (1 - in_prob) * power_calc_leakage_st(NMOS, NMOS_size);

    power_usage->leakage += in_prob * power_calc_leakage_gate(NMOS, NMOS_size)
            + (1 - in_prob) * power_calc_leakage_gate(PMOS, PMOS_size);
}

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void power_usage_inverter_irregular	(	t_power_usage *	power_usage,
		float *	dyn_power_input,
		float	in_density,
		float	in_probability,
		float	PMOS_size,
		float	NMOS_size,
		float	period
	)

Calculates the power of an inverter, with irregular P/N ratio

• power_usage: (Return value) The power usage of the inverter
• dy_power_input: (Return value) The dynamic power of the input node
• in_dens: The transition density of the input
• in_prob: The signal probability of the input
• PMOS_size: (W/L) of the PMOS
• NMOS_size: (W/L) of the NMOS

Definition at line 149 of file power_lowlevel.c.

                                                        {
    float C_drain, C_gate, C_source;
    float C_inv;
    float C_in;

    power_usage->dynamic = 0.;
    power_usage->leakage = 0.;

    C_inv = 0.;
    C_in = 0.;

    power_calc_transistor_capacitance(&C_drain, &C_source, &C_gate, NMOS,
            NMOS_size);
    C_inv += C_gate + C_drain;
    C_in += C_gate;

    power_calc_transistor_capacitance(&C_drain, &C_source, &C_gate, PMOS,
            PMOS_size);
    C_inv += C_gate + C_drain;
    C_in += C_gate;

    power_usage->dynamic = power_calc_node_switching(C_inv, in_density, period);
    *dyn_power_input = power_calc_node_switching(C_in, in_density, period);

    power_usage->leakage = in_probability
            * power_calc_leakage_st(PMOS, PMOS_size)
            + (1 - in_probability) * power_calc_leakage_st(NMOS, NMOS_size);
}

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void power_usage_level_restorer	(	t_power_usage *	power_usage,
		float *	dyn_power_in,
		float	in_dens,
		float	in_prob,
		float	period
	)

This function calculates the power of a level restorer, which is a biased inverter with a pull-up PMOS transistor in feedback.

• power_usage: (Return value) Power usage of the level restorer
• dyn_power_in: (Return value) Dynamic power at the input
• in_density: Transition density of the input
• in_prob: Signal probability of the input

Definition at line 740 of file power_lowlevel.c.

                                                                          {
    t_power_usage sub_power_usage;
    float C;
    float C_in;
    float input_dyn_power = 0.;

    power_zero_usage(power_usage);

    /* Inverter */
    power_usage_inverter_irregular(&sub_power_usage, &input_dyn_power, in_dens,
            in_prob, 1.0, 2.0, period);
    power_add_usage(power_usage, &sub_power_usage);

    /* Pull-up PMOS */
    if (g_power_tech->PMOS_inf.long_trans_inf == NULL) {
        power_log_msg(POWER_LOG_ERROR,
                "No long transistor information exists.  Cannot determine transistor properties.");
        return;
    }
    C = g_power_tech->PMOS_inf.long_trans_inf->C_d
            + g_power_tech->PMOS_inf.long_trans_inf->C_g;
    C_in = g_power_tech->PMOS_inf.long_trans_inf->C_d;

    input_dyn_power += power_calc_node_switching(C_in, in_dens, period);
    power_usage->dynamic += power_calc_node_switching(C, in_dens, period);
    power_usage->leakage += (1 - in_prob)
            * g_power_tech->PMOS_inf.long_trans_inf->leakage_subthreshold;

    *dyn_power_in = input_dyn_power;
}

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void power_usage_MUX2_transmission	(	t_power_usage *	power_usage,
		float	size,
		float *	in_dens,
		float *	in_prob,
		float	sel_dens,
		float	out_dens,
		float	period
	)

Calculates the power of a 2-input multiplexer, comprised of transmission gates

• power_usage: (Return value) Power usage of the mux
• in_dens: Array of input transition densities
• in_prob: Array of input signal probabilities
• sel_desn: Transition density of select line
• sel_prob: Signal probability of select line
• out_dens: Transition density of the output

Definition at line 445 of file power_lowlevel.c.

                      {

    power_zero_usage(power_usage);

    float leakage_n, leakage_p;
    leakage_n = power_calc_leakage_st(NMOS, size);
    leakage_p = power_calc_leakage_st(PMOS, size * g_power_tech->PN_ratio);

    float C_g_n, C_d_n, C_s_n;
    power_calc_transistor_capacitance(&C_d_n, &C_s_n, &C_g_n, NMOS, size);

    float C_g_p, C_d_p, C_s_p;
    power_calc_transistor_capacitance(&C_d_p, &C_s_p, &C_g_p, PMOS,
            size * g_power_tech->PN_ratio);

    /* A transmission gate leaks if the selected input != other input  */
    power_usage->leakage += (in_prob[0] * (1 - in_prob[1])
            + (1 - in_prob[0]) * in_prob[1]) * (leakage_n + leakage_p);

    /* Gate switching */
    power_usage->dynamic += 2
            * power_calc_node_switching(C_g_n + C_g_p, sel_dens, period);

    /* Input switching */
    power_usage->dynamic += power_calc_node_switching(C_d_n + C_s_p, in_dens[0],
            period);
    power_usage->dynamic += power_calc_node_switching(C_d_n + C_s_p, in_dens[1],
            period);

    /* Output switching */
    power_usage->dynamic += power_calc_node_switching(2 * (C_s_n + C_d_p),
            out_dens, period);
}

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void power_usage_mux_singlelevel_dynamic	(	t_power_usage *	power_usage,
		int	num_inputs,
		float	out_density,
		float	v_out,
		float *	in_prob,
		float *	in_dens,
		float *	v_in,
		float	sel_dens,
		float	sel_prob,
		float	transistor_size,
		float	period
	)

This function calculates the power of a single-level multiplexer, where the select lines are dynamic

• power_usage: (Return value) The power usage of the mux
• num_inputs: Number of multiplexer inputs (must be 2)
• out_density: The transition density of the output
• out_prob: The signal probability of the output
• v_out: The output max voltage
• in_prob: Array of input signal probabilities
• in_dens: Array of input tranistion densities
• v_in: Array of input voltages
• sel_dens: Transition density of the select line
• sel_prob: Signal probability of the select line
• tranisistor_size: NMOS transistor sizes (must be 1.0)

Definition at line 688 of file power_lowlevel.c.

                                             {

    assert(num_inputs == 2);

    power_zero_usage(power_usage);

    /* Leakage occurs when input1 != input2.
     * If the selected input is low, the other transistor leaks input->output
     * If the selected input is high, the other transistor leaks output->input*/

    /* 1st selected, 1st Low, 2nd High - Leakage from 2nd in->out */
    power_usage->leakage += (1 - sel_prob) * (1 - in_prob[0]) * in_prob[1]
            * power_calc_leakage_st_pass_transistor(transistor_size, v_in[1]);

    /* 1st selected, 1st High, 2nd Low - Leakage from 2nd out->in */
    /* 2nd selected, 1st Low, 2nd High - Leakage from 1st out->in */
    power_usage->leakage += ((1 - sel_prob) * in_prob[0] * (1 - in_prob[1])
            + sel_prob * (1 - in_prob[0]) * in_prob[1])
            * power_calc_leakage_st_pass_transistor(transistor_size, v_out);

    /* 2nd selected, 1st High, 2nd Low - Leakage from 1st in->out */
    power_usage->leakage += sel_prob * in_prob[0] * (1 - in_prob[1])
            * power_calc_leakage_st_pass_transistor(transistor_size, v_in[0]);

    /* Gate switching */
    float C_d, C_s, C_g;
    power_calc_transistor_capacitance(&C_d, &C_s, &C_g, NMOS, transistor_size);
    power_usage->dynamic += 2
            * power_calc_node_switching(C_g, sel_dens, period);

    /* Input switching */
    power_usage->dynamic += power_calc_node_switching_v(C_d, in_dens[0], period,
            v_in[0]);
    power_usage->dynamic += power_calc_node_switching_v(C_d, in_dens[1], period,
            v_in[1]);

    /* Output switching */
    power_usage->dynamic += power_calc_node_switching_v(2 * C_s, out_density,
            period, v_out);
}

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void power_usage_mux_singlelevel_static	(	t_power_usage *	power_usage,
		float *	out_prob,
		float *	out_dens,
		float *	v_out,
		int	num_inputs,
		int	selected_idx,
		float *	in_prob,
		float *	in_dens,
		float *	v_in,
		float	transistor_size,
		boolean	v_out_restored,
		float	period
	)

Calucates the power of a static, single-level multiplexer

• power_usage: (Return value) power usage of the mux
• out_prob: (Return value) Signal probability of the output
• out_dens: (Return value) Transition density of the output
• num_inputs: Number of inputs of the mux
• selected_idx: The input index that is selected by the select lines
• in_prob: Array of input signal probabilities
• in_dens: Array of input tranistion densities
• v_in: Array of input max voltages
• transistor_size: Size of the NMOS transistors (must be 1.0)
• v_out_restored: Whether the output will be level restored to Vdd

Definition at line 494 of file power_lowlevel.c.

                                                                     {
    int input_idx;
    float v_in_selected;
    float in_prob_avg;

    power_zero_usage(power_usage);

    assert(transistor_size >= 1.0);

    if (selected_idx < num_inputs) {
        *out_prob = in_prob[selected_idx];
        *out_dens = in_dens[selected_idx];
        v_in_selected = v_in[selected_idx];

    } else {
        /* In this case, the multiplexer is not symetrical.  The
         * other branch of the mux has more inputs than this one,
         * and the selected input index is not a valid index for
         * this portion of the mux.  If the mux was actually built
         * this way, there would likely be a weak pull-up to ensure
         * that the node does not float.
         */
        *out_prob = 1.0;
        *out_dens = 0.0;

        v_in_selected = 0.;
        for (input_idx = 0; input_idx < num_inputs; input_idx++) {
            v_in_selected += v_in[input_idx];
        }
        v_in_selected /= num_inputs;
    }

    in_prob_avg = 0.;

    float C_d, C_g, C_s;
    power_calc_transistor_capacitance(&C_d, &C_s, &C_g, NMOS, transistor_size);

    for (input_idx = 0; input_idx < num_inputs; input_idx++) {
        /* Dynamic Power at Inputs */
        power_usage->dynamic += power_calc_node_switching_v(C_d,
                in_dens[input_idx], period, v_in[input_idx]);

        if (input_idx != selected_idx) {
            in_prob_avg += in_prob[input_idx];
        }
    }
    in_prob_avg /= (num_inputs - 1);

    if (v_out_restored) {
        *v_out = g_power_tech->Vdd;
    } else {
        *v_out = power_calc_mux_v_out(num_inputs, transistor_size,
                v_in_selected, in_prob_avg);
    }

    for (input_idx = 0; input_idx < num_inputs; input_idx++) {
        /* Leakage */
        /* The selected input will never leak */
        if (input_idx == selected_idx) {
            continue;
        }

        /* Output is high and this input is low */
        power_usage->leakage += (*out_prob) * (1 - in_prob[input_idx])
                * power_calc_leakage_st_pass_transistor(transistor_size,
                        *v_out);

        /* Output is low and this input is high */
        power_usage->leakage += (1 - *out_prob) * in_prob[input_idx]
                * power_calc_leakage_st_pass_transistor(transistor_size,
                        v_in[input_idx]);
    }

    /* Dynamic Power at Output */
    power_usage->dynamic += power_calc_node_switching_v(C_s * num_inputs,
            *out_dens, period, *v_out);

}

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void power_usage_wire	(	t_power_usage *	power_usage,
		float	capacitance,
		float	density,
		float	period
	)

Calculates the power of a wire

• power_usage: (Return value) Power usage of the wire
• capacitance: Capacitance of the wire (F)
• density: Transition density of the wire

Definition at line 429 of file power_lowlevel.c.

                                     {
    power_usage->leakage = 0.;
    power_usage->dynamic = power_calc_node_switching(capacitance, density,
            period);
}

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