Hittite HMC440QS16G phase detector/divider

[biff44]

hittite hmc440qs16g

Anybody ever use this chip? It is a divide by 2 thru 32, with a phase detector built in. I am getting a pretty consistent ~100 mv voltage differential between the up and down outputs. Its driving the integrator bonkers at PLL startup! Anyone see the same thing, or solve the problem?

 

[mhampson]

Hi Biff,

Have you had any luck yet with that part? What do you mean by "it's driving the integrator bonkers?" Is the 100mV differential when your loop is locked?

I was thinking about using the similar HMC439QS16G in a translation loop design. How does the 440 respond to very wide pull-in/aqcuisition?

I will be laying out a board soon to try this out...

 

[biff44]

I never got it to work right. It could be poor soldering broke the chips, or that lot of chips were bad, or the thing just does not work. Obviously, if you have an integrator loop filter and the phase detector has a huge offset, when you turn on the power suppy the VCO tune voltage pegs at the supply rail, and it never locks up. By jiggering with a temporary current source into the op amp summing junction, I could get it to lock, so the loop parameters were stable. I am kind of PO'd. It cost me a big follow on job.

If I were you, I would buy their populated protoboard and try it for yourself. Maybe you will have better luck. At the very least, I would leave pads in the design for a potentiometer to manually balance the two pull up currents at the chip output!