The VCO is a current-starved ring oscillator with a variable number of stages. The digital inputs s0 and s1 determine the number of stages. The analog vcont input controls the frequency by adjusting the amount of current received by the inverters.
The PFD takes two input signals and uses the difference in phase+frequency to drive a charge pump.
Apply a voltage between 1.0V and 1.8V to vcont (ua0) and observe the oscillator output on uo0.
Apply two reference signals to the inputs ui2 and ui3 and observe the voltage change on vout (ua1).
An osilloscope, function generator, and a benchtop power supply would be handy but are not required.
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | vco0_s0 | vco0_out | |
| 1 | vco0_s1 | ||
| 2 | pfd0_clk | ||
| 3 | pfd0_ref | ||
| 4 | |||
| 5 | |||
| 6 | |||
| 7 |
ua# |
analog# |
Description |
|---|---|---|
| 0 | 0 | vco0_vcont |
| 1 | 5 | pfd0_vout |