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US 4,792,989 AGranted
Tuner circuits and voltage generators therefor
AssigneePlessey Overseas Limited
InventorNicholas P. Cowley
Life of this patent
Estimating the term…
Abstract
In a tuner circuit, the relatively high voltage used to control a varactor diode of the circuit is derived using a cascade of resistors and transistors under the control of a reference voltage input. The breakdown voltage of each transistor is significantly less than the output voltage of the cascade and is such that the cascade can be implimented in the same semiconductor chip as high frequency, low voltage process, synthesiser components.
Claims6
A tuner circuit comprising:
- a mixer having a reference input, a signal input and a signal output;
- a local oscillator connected to the reference input of said mixer;
- a varactor diode in the local oscillator, for controlling the frequency thereof;
- and,
- a synthesiser, including high frequency low voltage process components, responsive to said local oscillator, and, arranged to supply a control voltage to said varactor diode;
- and
- a voltage generator, integrated as part of said synthesiser in a common semiconductor chip, which voltage generator includes:
- a first series of resistive elements;
- a first series of transistors, the control electrodes of which transistors are connected to corresponding ones of said resistive elements;
- a second series of transistors connected in series with said first series of resistive elements;
- and,
- a second series of resistive elements connected in series with said first series of transistors, respective resistive elements thereof being connected to respective control electrodes of said second series of transistors, the last resistive element thereof being connected to receive a reference voltage;
- whereby, said control voltage is made available at, or near the connection between said first series of transistors and said second series of resistive elements.
10 more elements
A tuner circuit comprising:
- a mixer having a reference input, a signal input and a signal output;
- a local oscillator connected to the reference input of said mixer;
- a varactor diode in the local oscillator, for controlling the frequency thereof;
- a filter;
- at least one additional varactor diode, in said filter, to control the same;
- and,
- a synthesiser, including high frequency low voltage process components, responsive to said local oscillator, arranged to supply respective control voltages to each of said varactor diode and each said at least one additional varactor diode;
- a voltage generator, integrated as part of said synthesiser in a common semiconductor chip, which voltage generator includes a plurality of transistor cascades each of which includes:
- a first series of resistive elements;
- a first series of transistors, the control electrodes of which transistors are connected to corresponding ones of said resistive elements;
- a second series of transistors connected in series with said first series of resistive elements;
- and,
- a second series of resistive elements connected in series with said first series of transistors, respective resistive elements thereof being connected to respective control electrodes of said second series of transistors, the last resistive element thereof being connected to receive a common reference voltage;
- whereby, respective control voltages are made available at, or near the connections between said first series of transistors and said second series of resistive elements, in each transistor cascade.
11 more elements
Dependencies are inferred from the claim text.