Steering of high frequency low level photocurrents between summing busses beyond the gm/2πC limit

摘要

A 100 element photosensor signal processor has been developed that allows the detection and steering of A-O deflected high frequency (up to 1GHz) photogenerated signals between two output summing busses. Such a detector architecture provides the vehicle for summing a single or several preselected frequency bands from amongst 100 contiguous frequency band intervals on a preselected summing bus. All the frequency intervals not selected are automatically summed on the second summing bus. A Bragg cell is used to deflect monotonically, with frequency, a laser beam across the 100 detector elements according to the R-F frequency applied to the transducer attached to the Bragg cell. This A-0 arrangement provides the means for distributing the deflected laser beam across the 100 element photosensor in a monotonic frequency ensemble consisting of 100 contiguous frequency band intervals. The combination of the 100 element photosensor chip with a Bragg cell can be used to produce a spectrum analyzer and/or an electronically programmable filter bank for excising certain R-F frequencies. The photodetector's output signals are steered to a preselected suming bus by electric field switches which have a wide band frequency response.The wide band frequency response is possible even though the signal currents are very small (< 10-6amps) and would be limited to the gm/2ΠC frequency corner normally inherent with conventional transistor switches.