Pseudo digital gain control for broadband tuner
First Claim
1. A circuit comprising:
- a digital control circuit responsive to a digital control signal for providing a plurality of discrete selector signals;
a level control circuit responsive to said discrete selector signals for controlling a level of an input signal to provide an output signal;
a moderating circuit connected to said digital control circuit and said level control circuit for moderating a transition in said level of said input signal between signal levels, wherein said moderating circuit transmits each of said discrete selector signals from said digital control circuit to said level control circuit as a sequence of intermediate incremental changes in response to each change in level initiated by said digital control circuit; and
a plurality of latch circuits, each connected to transmit a respective one of said discrete selector signals to said level control circuit and configured to latch said discrete selector signals to a selected level upon completion of a level transition period, wherein said plurality of latch circuits remain passive during a transition in said level.
6 Assignments
0 Petitions
Accused Products
Abstract
A digital level control circuit, such as an Automatic Gain Control, includes a plurality of digitally selectable signal levels with transitions between levels gradually varied to avoid signal output level discontinuities. An up/down counter may be used to incrementally stepwise transition an output signal between the digitally selectable output levels. Stepwise application of a control signal to the appropriate switching elements (e.g., FETs) forming an attenuator circuit may be implemented to moderate a switching time of the switching elements to provide a more gradual transition between element operating states. A deglitch circuit may be employed to latch the switching elements to achieve the desired state at the end of a desired switching transition period.
-
Citations
19 Claims
-
1. A circuit comprising:
-
a digital control circuit responsive to a digital control signal for providing a plurality of discrete selector signals; a level control circuit responsive to said discrete selector signals for controlling a level of an input signal to provide an output signal; a moderating circuit connected to said digital control circuit and said level control circuit for moderating a transition in said level of said input signal between signal levels, wherein said moderating circuit transmits each of said discrete selector signals from said digital control circuit to said level control circuit as a sequence of intermediate incremental changes in response to each change in level initiated by said digital control circuit; and a plurality of latch circuits, each connected to transmit a respective one of said discrete selector signals to said level control circuit and configured to latch said discrete selector signals to a selected level upon completion of a level transition period, wherein said plurality of latch circuits remain passive during a transition in said level. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A circuit comprising:
-
a digital switch including a plurality of switching elements, said digital switch responsive to a digital control signal for controlling said switching elements to control a level of an output signal to one of a plurality of selectable level values; a moderating circuit connected to said switching elements and supplying an analog control signal thereto so as to cause said switching elements to transition between conducting states in response to said digital control signal over an appropriate period of time; and a deglitch circuit connected to said moderating circuit and to said switching elements of said digital switch, said deglitch circuit configured to coordinate control signals between said moderating circuit and said switching elements such that a minimum number of transitions are permitted to occur at one time. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A circuit for controlling an output level of a signal comprising:
-
a plurality of switching elements connected to receive an input signal and selectively control a level of said input signal to provide an output signal; a moderating circuit connected to said switching elements, said moderating circuit including a counter and selectively providing a monotonically changing signal level to a switching element of said switching elements in response to said counter to cause said switching element to change conduction states over some finite transition period, whereby said switching element incrementally transitions between an open and close conduction state; and a plurality of latch circuits connected between said plurality of switching elements and said moderating circuit configured to latch a selected level to said plurality of switching elements upon completion of a transition period, wherein said plurality of latch circuits remain passive during a transition in said level.
-
-
19. A tuner comprising:
-
a radio frequency (RF) input stage; an RF converter stage connected to said RF input stage and receiving an RF signal therefrom to provide an intermediate frequency (IF) signal; an IF stage including an automatic gain control circuit (A.G.C.), said A.G.C. including; (i) a digital control circuit responsive to a digital control signal for providing a plurality of discrete selector signals; (ii) a level control circuit responsive to said discrete selector signals for controlling a level of said IF signal; and (iii) a moderating circuit connected to said digital control circuit and said level control circuit for moderating a transition in said level of said IF signal between signal levels, wherein said moderating circuit transmits each of said discrete selector signals from said digital control circuit to said level control circuit as a sequence of intermediate incremental changes to cause switching elements of the level control circuit to incrementally transition between open and close conduction states; and a signal detector demodulating said IF signal to provide an output signal.
-
Specification