A leaky integrator is used to measure the averaged signal magnitude over a period of time. The leaky integrator time constant is programmable from a single T4/T8 clock cycle to 216 clock cycles.
The transform function of the leaky integrator is showed as following:
- y[n]=(1-1/2λ)y[n-1]+1/2λ |x[n]|
where:
y[n] is the output of leaky integrator
y[n-1] is the last output of leaky integrator
x[n] is the current input value; the output from input stage
2λ is the time constant.
The following table gives the programmable time constant values:
Lambda Index | Lambda Value | Time Constant (T4/T8 Cycle) |
---|---|---|
0 | 0 | 2^0 |
1 | 2 | 2^2 |
2 | 4 | 2^4 |
3 | 8 | 2^8 |
4 | 12 | 2^12 |
5 | 14 | 2^14 |
6 | 16 | 2^16 |
7 | N/A | N/A |
A Gauss distribution signal is used for illustration in above figure. A set of curves base on different time constant shows the 20*log10 outputs of the leaky integrator.
A user programmable flush bit can be used to flush the leaky integrator which reset the value to 0.