Low cost amplitude measurement circuit up to 10MHz

[poorchava]

I need a circuit which will convert a sine of variable frequency (from few Hz to 10MHz) to a proportional dc voltage. For a lower frequency I'd go for a classical ideal rectifier circuit based on a high speed comparator. While this seams to be feasible for 10 MHz signal using very high speed comparator (5ns ones are generally available), i'm looking for some lower cost solution. I't might even be done with discrete components.

All ideas and suggestions are welcome

 

[FvM]

I don't see a purpose of comparators in this regard (in contrast to opamps). Possibly, a "passive" diode rectifier may be sufficient. Unfortunately, you didn't mention intended accuracy and dynamic range.

 

[poorchava]

Dynamic range from 50 mV to 5V. Accuracy of 10mV would be satisfactory.