I'm testing the DC1646A (demo board for the RF power detector LTC5564) and I'm having trouble getting a clean VCOMP. I'm not sure if it is due to noise or if I need to adjust some elements of the demo PCB.
I'm attaching some measurements. Parameters:
VCC = 5V, RFIN = 5.8 GHz, input power at the demo board 0 dBm.
CH1 (yellow) is VOUT
CH2(cyan) is VCOMP.
GAIN 1, otherwise I will specify it.
- NO RFIN.
- RFIN ON.
- RFIN OFF. (Now also showing VCOMP)
- RFIN OFF, VREF = 0.34V. Notice how VOUT has some transients and VCOMP goes high. The threshold, VREF 340 mV, is far from the 282 mV of VOUT.
-RFIN ON, VREF = 0.34 V. Looks like VOUT is noisy when VREF is ON. VCOMP is HIGH (makes sense since VOUT>>VREF)
-RFIN ON, VREF = 0.84 V. Now VCOMP is LOW (makes sense since VOUT<VREF)
-RFIN ON, VREF = 0.470 V. Now VCOMP is going LOW too often. As far as I understand, this is not how it should be since VOUT>VREF.
- RFIN ON, VREF = 0.70 V. Now VCOMP is going HIGH sometimes. As far as I understand, this is not how it should be since VOUT<<VREF.
Is this how it is supposed to work? I'm using a R&S lab power supply, I'm assuming it is a fairly clean power supply.