Mixer

Block: Mixer (mixer)
Block Author: Aaron Parsons
Document Author: Aaron Parsons, Ben Blackman

Contents

Summary
Mask Parameters
Ports
Description
- Usage

Summary

Digitally mixes an input signal (which can be several samples in parallel) with an LO of the indicated frequency (which is some fraction of the native FPGA clock rate).

Mask Parameters

Parameter	Variable	Description
Frequency Divisions	freq_div	The (power of 2) denominator of the mixing frequency.
Mixing Frequency	freq	The numerator of the mixing frequency.
Number of Parallel Streams	nstreams	The number of samples that arrive in parallel.
Bit Width	n_bits	The bitwidth of LO samples.
BRAM Latency	bram_latency	The latency of sin/cos lookup table.
MULT Latency	mult_latency	The latency of mixing multipliers.

Ports

Port	Dir	Data Type	Description
sync	IN	boolean	Takes in an impulse the cycle before the `din`s are valid.
dinX	IN	Fix_8_7	Input X to be mixed and output on `realX` and `imagX`.
sync_out	OUT	boolean	This signal will be high the cycle before the data coming out is valid.
realX	OUT	Fix_(n_bits)_(n_bits-1)	Real output of mixed `dinX`.
imagX	OUT	Fix_(n_bits)_(n_bits-1)	Imaginary output of mixed `dinX`.

Description

Usage

Mixer mixes the incoming data and produces both real and imaginary outputs.

M = Frequency Divisions

F = Mixing Frequency

M and F must both be integers, and M must be a power of 2. The ratio F/M should equal the ratio f/r where r is the data rate of the sampled signal. For example, an F/M of 3/16 would downmix an 800Msps signal with an LO of 150MHz.