CN203151452U - DDS output signal amplitude regulation and control circuit based on DCPs - Google Patents

Abstract

The utility model discloses a DDS output signal amplitude regulation and control circuit based on DCPs, which comprises an MCU, a DDS, four same-model DCPs, a DDS load resistor R1, and a DDS load resistor R2. The DDS output signal amplitude regulation and control circuit is characterized by further comprising two auxiliary resistors R3 and R4; DCP1 and DCP2 is in parallel connection; DCP3 and DCP4 are in parallel connection; two parallel-connection DCP groups are then serially connected and further connected with the resistor R3 in a parallel way to form an equivalent DCP; the MCU controls the tap changes of the DCPs and changes the resistance of the equivalent DCP to initiate a DAC full-scale current change inside the DDS; and the aim of adjusting the output signal amplitude is achieved. By adopting a combination of DCP serial connection and DCP parallel connection, the DDS output signal amplitude regulation and control circuit achieves regulation and control on the DDS output signal amplitude in a high-resolution and relatively wide range way.

Description

DDS amplitude output signal circuit for regulating and controlling based on DCP

Technical field

The utility model relates to the signal amplitude control technique of electronic information field, particularly a kind of DDS amplitude output signal circuit for regulating and controlling based on DCP.

Background technology

DDS is as Direct Digital Synthesizer, and output frequency is easy to adjust, and low in energy consumption, resolution is high, change-over time is short, is designed to signal generator usually, be widely used in communication with electronic equipment in.In many equipment, the amplitude of signal is to need to change, but owing to be subjected to the restriction of performance index and circuit complexity, commercial DDS chip does not arrange direct amplitude adjusted function.

For addressing this problem, method commonly used is that output at DDS adds the amplification circuit at present, and the gain by the control amplifying circuit realizes the regulation and control to signal amplitude.This method is convenient to realize the amplitude adjusted of large-signal, and is difficult to regulate and control the amplitude of small-signal.And circuit is comparatively complicated, the cost height; After introducing amplifier, the noiseproof feature of signal also can obviously descend.Summary of the invention

In order to overcome the shortcoming of above-mentioned technical problem, the utility model provides that a kind of circuit is simple, regulation and control are flexibly based on the DDS amplitude output signal circuit for regulating and controlling of DCP.

DDS amplitude output signal circuit for regulating and controlling based on DCP of the present utility model, comprise microcontroller MCU, for generation of the DDS of setpoint frequency signal, be used for 4 same model DCP, the DDS output load resistance R of DAC full scale electric current in the control DDS sheet ₁And R ₂, its special feature is: also comprise auxiliary resistance R ₃, R ₄The R of DCP1 among described 4 same model DCP _W, R _LEnd respectively with the R of DCP2 _W, R _LEnd is in parallel, the R of DCP3 _W, R _LEnd respectively with the R of DCP4 _W, R _LEnd is in parallel; The R of DCP2 _LEnd is linked the R of DCP3 _WEnd; The R of DCP1 _WThe R of end and DCP4 _LAuxiliary resistance R in parallel between the end ₃The R of DCP1 _WDAC full scale electric current arranges pin DAC R in the sheet of termination DDS _Set, the R of DCP4 _LTermination auxiliary resistance R ₄An end, R ₄Other end ground connection; The R of all DCP _HHold all unsettled; The output frequency of the DDS of described MCU and the tap position of 4 DCP are controlled; DCP1 is identical all the time with the tap position of DCP2, and DCP3 is identical all the time with the tap position of DCP4.

DDS amplitude output signal circuit for regulating and controlling based on DCP of the present utility model, DCP1 is in parallel with DCP2 among described 4 same model DCP, and DCP3 is in parallel with DCP4; The DCP of two groups of parallel connections connects again, and with auxiliary resistance R ₃Parallel connection constitutes an equivalent DCP; The value of the tap position n of this equivalence DCP changes with the change of each DCP tap position, its equivalent resistance R _EWith current-limiting resistance R ₄Total resistance R after the series connection also changes thereupon, and the variation of R causes that DAC full scale electric current I changes in the DDS sheet, and the DDS amplitude output signal is followed the proportional variation of I.

The beneficial effects of the utility model are: by the series and parallel combination of 4 same model digital regulation resistance DCP, constitute a high-resolution, high-precision equivalent DCP and go to control the variation of DAC full scale electric current in the DDS sheet, realize the high-resolution of DDS amplitude output signal, the flexible regulation and control of wide region.

Description of drawings

Accompanying drawing is electric theory diagram of the present utility model.

Among the figure: 1MCU, 2 Direct Digital Synthesizer DDS, 3 the 1st digital regulation resistance DCP1,4 the 2nd digital regulation resistance DCP2,5 the 3rd digital regulation resistance DCP3,6 the 4th digital regulation resistance DCP4,7 equivalent DCP.

Embodiment

By reference to the accompanying drawings, DDS amplitude output signal circuit for regulating and controlling based on DCP of the present utility model, it comprises MCU (1), DDS (2), first digit potentiometer DCP1 (3), second digit potentiometer DCP2 (4), third digit potentiometer DCP3 (5), fourth digit potentiometer DCP4 (6), auxiliary resistance R ₃And R ₄, the load resistance R of DAC in the DDS sheet ₁And R ₂4 shown digital regulation resistance DCP models are identical, the R of DCP1 _W, R _LEnd respectively with the R of DCP2 _W, R _LEnd is in parallel, the R of DCP3 _W, R _LEnd respectively with the R of DCP4 _W, R _LEnd is in parallel; The R of DCP2 _LEnd is linked the R of DCP3 _WEnd is together in series the DCP of two groups of parallel connections; The R of DCP1 _WThe R of end and DCP4 _LAuxiliary resistance R in parallel again between the end ₃The R of DCP1 _WDAC full scale electric current arranges pin DAC R in the termination DDS sheet _SetThe R of DCP4 _LTermination auxiliary resistance R ₄An end, R ₄Other end ground connection; The R of all DCP _HHold all unsettled; The tap position of the output frequency of the DDS of MCU and 4 DCP is controlled; DCP1 is identical all the time with the tap position of DCP2, and DCP3 is also identical all the time with the tap position of DCP4.

Direct Digital Synthesizer DDS is for generation of the signal output of setpoint frequency; The DCP series connection of two groups of parallel connections is then with auxiliary resistance R ₃Parallel connection constitutes a high-resolution, high-precision equivalent DCP; If the all-in resistance of each DCP is R _T, tap number is t, the variable resistance of equivalent DCP is R _EBy equivalent DCP circuit is analyzed, can draw its equivalent resistance and be:

$R_E=\frac{n{R}_T}{2(t-1)}//R_3\·\·\·\left(1\right)$

The actual tap position n round numbers of this equivalence DCP, span are 0 to 2 (t-1); The change of each DCP tap position causes that the value of the tap position n of equivalent DCP changes equivalent resistance R _EChange thereupon.

The full scale electric current that provides according to the DDS databook calculates Coefficient m, and the expression formula that can obtain DAC full scale electric current I in the DDS sheet is:

$I=\frac{m}{R_E+R_4}=\frac{m}{[\frac{n{R}_T}{2(t-1)}//R_3]+{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="HSA00000865567400011.png"\; state="\{\{state\}\}">R</figure-callout>}}_4}\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

Equivalent resistance R _EWith current-limiting resistance R ₄Total resistance R after the series connection changes with tap position n, and the variation of R causes that DAC full scale electric current I changes in the DDS sheet, and the DDS amplitude output signal is followed the proportional variation of I.

The parallel connection of DCP makes the resistance adjustment resolution of equivalent DCP by R _T/ (t-1) being doubled, the regulation and control resolution of DDS amplitude output signal is improved; The DCP series connection of two groups of parallel connections makes total tap number of equivalent DCP expand to (2t-1) by t, has enlarged the modification scope of DDS amplitude output signal; Auxiliary resistance R in parallel ₃Help to improve the variation linearity of I, improve the control accuracy of DDS amplitude output signal; The auxiliary resistance R of series connection ₄Limit the numerical value that arranges of I, avoid the excessive DDS of burning out because of I.

Claims (2)

1. based on the DDS amplitude output signal circuit for regulating and controlling of DCP, comprise microcontroller MCU, for generation of the DDS of setpoint frequency signal, be used for 4 same model DCP, the DDS output load resistance R of DAC full scale electric current in the control DDS sheet ₁And R ₂, it is characterized in that: also comprise auxiliary resistance R ₃, R ₄The R of DCP1 among described 4 same model DCP _W, R _LEnd respectively with the R of DCP2 _W, R _LEnd is in parallel, the R of DCP3 _W, R _LEnd respectively with the R of DCP4 _W, R _LEnd is in parallel: the R of DCP2 _LEnd is linked the R of DCP3 _WEnd; The R of DCP1 _WThe R of end and DCP4 _LAuxiliary resistance R in parallel between the end ₃: the R of DCP1 _WDAC full scale electric current arranges pin DACR in the sheet of termination DDS _Set, the R of DCP4 _LTermination auxiliary resistance R ₄An end, R ₄Other end ground connection; The R of all DCP _HHold all unsettled; The output frequency of the DDS of described MCU and the tap position of 4 DCP are controlled; DCP1 is identical all the time with the tap position of DCP2, and DCP3 is identical all the time with the tap position of DCP4.

2. the DDS amplitude output signal circuit for regulating and controlling based on DCP according to claim 1, it is characterized in that: DCP1 is in parallel with DCP2 among described 4 same model DCP, and DCP3 is in parallel with DCP4; The DCP of two groups of parallel connections connects again, and with auxiliary resistance R ₃Parallel connection constitutes an equivalent DCP.

Images