Telephonic communications – Supervisory or control line signaling – Signal reception at substation
Utility Patent
1997-07-02
2001-01-02
Chan, Wing F. (Department: 2743)
Telephonic communications
Supervisory or control line signaling
Signal reception at substation
C379S252000
Utility Patent
active
06169800
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates, in general, to integrated circuits and, more particularly, to ring detection amplifiers.
In a wireless communications device, such as a cellular phone or a pager, a transducer is activated when an incoming call is received. Prior to the incoming call, the quiescent current in the transducer is minimized to conserve power in the battery operated communications device. When the call is detected in the communications device, the output of a ring detection circuit or an alert detector is biased at about mid supply and a ring signal is transferred to the transducer. The incoming call causes a unidirectional current flow in the transducer that produces an audible ringing. Whether the ring signal is small, producing a quiet ring, or the ring signal is large, producing a loud ring, biasing the output of the alert detector at about mid supply causes significant current in the transducer compared to the standby currents in the wireless communication device.
Accordingly, it would be advantageous to have a ring detection circuit that has a minimal standby current. It would be of further advantage to bias the transducer at a bias reference voltage that minimizes current in the transducer during transfer of the ring signal from the input to the output of the ring detection circuit in the wireless communications device.
REFERENCES:
patent: 4349703 (1982-09-01), Chea, Jr.
patent: 4585999 (1986-04-01), Hilbert et al.
patent: 4656659 (1987-04-01), Chea, Jr.
patent: 4771450 (1988-09-01), Castro et al.
“Peak Detector Provides Both The Amplitude And A Peak-event Timing Pulse”, E. H. Smith, Jr., Electronic Design, Circle No. 311, Nov. 23, 1977, p. 140.
Chan Wing F.
Motorola Inc.
Parker Lanny L.
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