rockpool.devices.xylo.syns65302.afe.params

Design parameters for XyloAudio 3 Audio Frontend.

NOTE: Refer to the following documentation file for further details on the design https://spinystellate.office.synsense.ai/saeid.haghighatshoar/agc-for-xylo-v3/blob/master/README.md

Module Attributes

XYLO_MAX_AMP	Due to the differential design of the amplifier
SYSTEM_CLOCK_RATE	The system clock
AUDIO_SAMPLING_RATE	Audio sampling rate of ~48.8 kHz
AUDIO_SAMPLING_RATE_AGC	Audio sampling rate of ~50.0 kHz
NUM_BITS_AGC_ADC	Number of bits allocated for AGC path's digital output
NUM_BITS_PDM_ADC	Number of bits devoted to the final sampled audio obtained after low-pass filtering + decimation.
AUDIO_CUTOFF_FREQUENCY	The upper limit for human audio spectrum 20 kHz
AUDIO_CUTOFF_FREQUENCY_WIDTH	Used as transition widths, set to 20% of the cutoff frequency
PDM_FILTER_DECIMATION_FACTOR	Oversampling factor, how much the signal needs to be decimated or subsampled
PDM_SAMPLING_RATE	Sampling rate/clock rate of PDM module.
DELTA_SIGMA_ORDER	Order of the deltasigma modulator (conventional ones are 2 or 3)
DECIMATION_FILTER_LENGTH	Length of the designed FIR filter
NUM_BITS_FILTER_Q	Number of bits used for quantizing the filter coefficients
SETTLING_TIME_PGA	The settling time (due to working point variation) in PGA NOTE: this is at the moment less than half clock period.
HIGH_PASS_CORNER	high-pass corner due to AC coupling
LOW_PASS_CORNER	low-pass corner due to frequency response or low-pass filtering (e.g., anti-aliasing low-pass filter)
MAX_PGA_GAIN	maximum target gain for PGA
NUM_BITS_COMMAND	Number of bits assigned to command from envelope controller (EC) to programmable-gain amplifier (PGA)
EXP_PGA_GAIN_VEC	Gain vector used in the design of AGC NOTE: we use an exponential gain pattern but other gain patterns are also possible
DEFAULT_PGA_COMMAND_IN_FIXED_GAIN_FOR_PGA_MODE	We have a fixed-gain mode for PGA where PGA ignores the gain-change commands it receives from EC module.
RISE_TIME_CONSTANT	default rise time-constant used for estimating the envelope
FALL_TIME_CONSTANT	default fall time-constant used for estimating the envelope
SATURATION_LEVEL	Saturation level boundary NOTE: we should set the saturation level a little bit lower for two reasons (i) when it is low, the system is more cautious and, when the signal becomes strong suddenly, goes outside saturation very fast. (ii) at the moment, we are using an oversampled ADC with decimation filter where as a result of processing, the quantized signal may not have full rail-to-rail dynamics due to some inner attenuation. If we use a very large saturation level, the weak signal after attenuation may indeed be in saturation but not get detected by EC.
WAITING_TIME_VEC	Waiting times used for waiting before any gain switch
MAX_WAITING_TIME_BEFORE_GAIN_CHANGE	Maximum waiting time before change gain NOTE: This parameter makes sure that the gain change happens with at least some interval independent of how much it is delayed!
RELIABLE_MAX_HYSTERESIS	Reliable hysteresis in detecting the maximum NOTE: to make sure that waiting times are working well, we need to extend waiting times when the signal amplitude increase is significant we measure this by a hysteresis parameter which should be typically around 2 ~ 10 for an ADC with 10 bits
PGA_GAIN_INDEX_VARIATION	dynamics of the gain-change at each amplitude level
AMPLITUDE_THRESHOLDS	Threshold amplitude levels NOTE (1): here we are working with the exponential amplitude levels that match the exponential pattern of the gains sequence in PGA.
MAX_WAITING_BITWIDTH	what is the largest waiting time length covered by the XyloAudio 3 -> how many bits suffice?
INIFINITY_OF_TRANSIENT_PHASE	In gain smoother we need to adjust the gain slowly to avoid fast gain jump.
NUM_BITS_GAIN_QUANTIZATION	number of bits used for quantizing the gain ratio
NUM_FILTERS	Total number of filters in the filter bank
MAX_SPIKES_INPUT	Maximum number of spikes that input neurons can handle