In some embodiments, waveform generator circuitry 1340 may be fabricated at least in part on a semiconductor die. For example, as shown in FIG. 13C, oscillator 1341, signal splitter 1342, programmable digital divider 1344, digital control logic block 1346, and frequency mixer 1348 may be realized as integrated circuitry fabricated on a semiconductor die part of the interrogator. On the other hand, loop filter 1350 and fixed-frequency reference oscillator 1352 may be implemented off the semiconductor die, for example, as discrete components on a substrate. However, in other embodiments, all, none or a different subset of the components of waveform circuitry 1340 may be realized as integrated circuitry fabricated on a semiconductor die part of the interrogator. For example, in some embodiments, digital control logic block 1346 may be implemented off chip.
FIG. 9A is a block diagram illustrating components of a target device 900, in accordance with some embodiments of the technology described herein. In the illustrative embodiment of FIG. 9A, target device 900 includes receive antenna 122, signal transformation circuitry 124a, and transmit antenna 126. The output of receive antenna 122 is coupled, via line 902, to an input of signal transformation circuitry 124a. The output of signal transformation circuitry 124a is coupled, via line 914, to transmit antenna 126.
