Frequency to current converter circuit
First Claim
1. A circuit for converting a variable frequency cyclic input signal to a current output signal having a magnitude representative of the frequency of the input signal, the magnitude being a non-zero value for a frequency of zero Hertz, comprising:
- regulated supply means for providing a first non-zero regulated electrical signal and a second non-zero regulated electrical signal, the first and second regulated signals having different magnitudes;
switching means having a switching means output responsive to the input signal and coupled to the regulated supply means for alternately providing the first regulated signal and the second regulated signal at the switching means output for lengths of time which vary relative to one another depending upon the frequency of the input signal;
averaging means coupled to the switching means output to receive the first and second regulated signals for providing an average signal from the regulated signals; and
output means for providing a current output signal having a magnitude controlled by the average signal.
0 Assignments
0 Petitions
Accused Products
Abstract
A circuit (10) receives a cyclic input signal having a frequency determined by a source (11), which frequency may vary in accordance with a parameter or condition to be measured, for example. The circuit (10) very precisely provides an output current representative of the frequency of the input signal. In particular, the circuit uses a pair of regulated and different voltage (16)(17), one (16) of which is impressed upon an averaging circuit (30) for a preselected time during each cycle of the input signal, and the other voltage (17) is impressed upon the averaging circuit (30) during the time when the first signal is not connected to the averaging circuit. A control signal (Vo) is developed from the averaging circuit (30) which is a function of the average of the voltage provided to the averaging circuit, and the control signal (Vo) in turn is used for controlling a current control amplifier (60) and transistors (61)(62) which in turn control current flow through a load (40) connected to output terminals (36)(37) and through a feedback resistor (63). The use of regulated voltage sources (16)(17) for deriving the current control signal insures great stability, relatively low cost, and precise operation.
-
Citations
20 Claims
-
1. A circuit for converting a variable frequency cyclic input signal to a current output signal having a magnitude representative of the frequency of the input signal, the magnitude being a non-zero value for a frequency of zero Hertz, comprising:
-
regulated supply means for providing a first non-zero regulated electrical signal and a second non-zero regulated electrical signal, the first and second regulated signals having different magnitudes; switching means having a switching means output responsive to the input signal and coupled to the regulated supply means for alternately providing the first regulated signal and the second regulated signal at the switching means output for lengths of time which vary relative to one another depending upon the frequency of the input signal; averaging means coupled to the switching means output to receive the first and second regulated signals for providing an average signal from the regulated signals; and output means for providing a current output signal having a magnitude controlled by the average signal. - View Dependent Claims (2, 3, 4)
-
-
5. Means to provide an analog output current which has a magnitude controlled by the frequency of a cyclical input signal having a variable cycle time period so that the magnitude is a non-zero value when the frequency is zero Hertz, the means comprising:
-
first means for providing a first non-zero regulated electrical signal; second means for providing a second non-zero regulated electrical signal different from the first regulated signal; third means for providing the first signal for a predetermined length of time less than the cycle time period of the input signal at an upper frequency limit once during each cycle of the input signal; fourth means for providing the second regulated signal for a remainder of the cycle time period during each cycle of the input signal; and output means for receiving the first and second regulated signals from the third and fourth means including means for providing a control signal having a value which is a function of an average magnitude of the first and second regulated signals received by the output means during a reference time period and including means responsive to the control signal for providing the output current having a magnitude controlled by the control signal. - View Dependent Claims (6)
-
-
8. A signal frequency to current converter for providing an output current signal having a magnitude which is controlled by a frequency of a cyclical input signal having a cycle time period and which has a positive non-zero threshold value when the frequency of the input signal is zero, said converter comprising:
-
first means for providing a first non-zero voltage signal; second means providing a second non-zero voltage signal different from the first voltage signal; third means for providing a control signal; means for coupling the first means to the third means for a predetermined length of time which is less than the cycle time period once during each cycle of the input signal; means for coupling the second means to the third means for a portion of the cycle time period when the first means is not so coupled during each cycle of the input signal; said third means providing a control signal with a value which is a function of an average voltage provided to the third means by the first and second means during each cycle time period; and an output circuit coupled to the third means and including means responsive to the control signal to provide an output current having a magnitude controlled by the value of the control signal. - View Dependent Claims (7, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A frequency-to-current converter circuit for providing an output current with a magnitude which has a predetermined relationship to a frequency of a cyclic input signal, the circuit comprising:
-
means for providing a non-zero regulated first voltage; means for providing a non-zero regulated second voltage; means for alternately supplying the first and second voltages for first and second time periods, respectively, during each cycle, the first and second time periods having relative durations which are a function of the frequency of the input signal; means for averaging the first and second voltages supplied during the first and second time periods to produce an average voltage; means for providing a feedback voltage which is a function of the magnitude of the output current; and means for controlling the magnitude of the output current as a function of the average voltage and the feedback voltage so that the output current maintains the predetermined relationship to the frequency of the input signal.
-
-
19. A circuit for converting a cyclic input signal to an analog output signal having a magnitude representative of frequency of the input signal, the magnitude being a non-zero value when the frequency is zero Hertz, the circuit comprising:
-
regulated supply means for providing a first regulated electrical signal and a second regulated electrical signal, the first and second regulated signals having different non-zero magnitudes, wherein the regulated supply means comprises first and second adjusting means coupled to permit adjusting the magnitudes of the first and second regulated electrical signals; switching means having a switching means output responsive to the input signal and coupled to the regulated supply means for alternately providing the first regulated signal and the second regulated signal at the switching means output; averaging means coupled to the switching means output to receive the first and second regulated signals for providing an average signal from the regulated signals; and output means for providing a current output signal having a magnitude controlled by the average signal. - View Dependent Claims (20)
-
Specification