I have configured the AL5801 for broadband down conversion in a very similar manner to what is shown in Fig. 102 of the datasheet. VSET (pin10) is driven directly by DETO (pin 11) and no other bias is present on that pin (R10 and R9 in Fig. 102 are left open).
Some questions on this set up:
1. Can you please confirm that this is a valid mode of operation (DETO is providing automatic IIP3 control) and that the VSET pin does not require any other DC bias?
2. Since VSET is shorted to DETO, I assume that only one set of decoupling caps are needed - in Fig. 102 C17 and C18 can be left unpopulated as long as C1 and C12 are connected as shown. Is this correct?
3. In this configuration what is the current draw of the ADL5801 when the ENBL (pin 9) is high (detector and internal bias circuit turned off)?
4. In this configuration (VSET driven exclusively by DETO) and with ENBL set high, will the ADL5801 still function as a mixer? In other words, if a RF signal somehow makes it into the RF ports will it be down-converted and exit the LO ports? What would be the conversion gain of the device in such a case for say a LO of 1077 MHz as in Fig. 95?