Telecommunications – Transmitter – Frequency conversion
Patent
1985-12-17
1987-09-22
Ng, Jin F.
Telecommunications
Transmitter
Frequency conversion
455126, 455260, 455302, 455306, 307512, 307521, 328167, H04B 104, H04B 126, H04B 110
Patent
active
046960554
ABSTRACT:
A radio frequency tuning circuit, for use in a transmitter or receiver, which rejects image frequencies of the frequency band of a supplied RF signal to which it is tuned. The circuit comprises an N-path filter and a feedback loop connecting the output of such filter to the input of an RF amplifier to which the RF signal is applied. The filter includes a tunable local oscillator and a pair of quadrature related signal paths including mixers therein driven by such oscillator, the outputs of such paths being combined by a summing amplifier which produces the output RF signal. The output of the summing amplifier is also supplied to the feedback path, causing the center frequency of the transfer characteristic of the N-path filter to be displaced from the local oscillator frequency. The RF output signal thereby includes substantially only single sideband of the signals produced by the two signal paths.
REFERENCES:
patent: 3141134 (1964-07-01), Osborne et al.
patent: 3624513 (1971-11-01), Costas
patent: 3744015 (1973-07-01), Marimon et al.
patent: 4408351 (1983-10-01), Maurer et al.
patent: 4476585 (1984-10-01), Reed
"Network Theory", Edited by Boite, Authored by Saraga.
Briody Thomas A.
Ng Jin F.
Oisher Jack
Streeter William J.
U.S. Philips Corporation
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