CN203608182U - Wide input range linear voltage-to-time converter - Google Patents

Abstract

The utility model relates to the field of analog integrated circuit design of microelectronics and aims to enlarge the input range of a conventional VTC and enable the VTC to keep the linear characteristic within a large input range. According to the technical scheme, a wide input range linear voltage-to-time converter comprises two sampling switches Sh, two discharging switches Sd, two sampling capacitors CH or CL and Cref, two current sources I and two comparators Com1 and Com2, wherein H represents the word of high, and L represents the word of low. The two sampling switches Sh are switched on, and two sets of inputted analog voltage signals are sampled through the sampling capacitors CH or CL and Cref; then the sampling switches Sh are switched off, the discharging switches Sd are switched on, and the sampling capacitors are discharged within the specified time; and the comparators Com1 and Com2 detect voltage at the two terminals of each capacitor and compare the voltage with a comparison signal.

Description

Wide input range linear voltage time converter

Technical field

The utility model relates to microelectronic analog integrated circuit design field, particularly a kind of wide input range linear voltage time converter.

Technical background

Voltage time transducer (Voltage to time converter, VTC) is the important devices of time domain ADC.Voltage signal is converted to time signal by VTC, and the time of conversion is carried out digital quantization by late-class circuit again.The linearity and input range are the important indicators of weighing VTC performance.

At least there is following shortcoming and defect in above-mentioned technology:

The input range of the voltage time transducer that tradition proposes all only has tens to hundreds of millivolt, and be tens psecs corresponding change-over time, because only linear output of guarantee within the scope of this.In addition, the linearity of the voltage time transducer of mentioning in prior art is all limited to device transmission characteristic, and the linearity is difficult to be further enhanced.

Summary of the invention

For overcoming the deficiencies in the prior art, the utility model is intended to further increase the input range of traditional VTC, make VTC under larger input range, still can keep linear characteristic, for achieving the above object, the technical solution adopted in the utility model is, wide input range linear voltage time converter, comprise: two sampling switch Sh, two discharge switch Sd, two sampling capacitance CH or CL and Cref, H wherein represents high, and L represents low; Two current source I and two comparator C om1 and Com2;

Termination analog input VH or a VL of first sampling switch Sh, one end of one end of another termination sampling capacitance CH or CL and first discharge switch Sd, the other end ground connection of sampling capacitance CH or CL, the inflow end of first current source of another termination I of first discharge switch Sd and the negative terminal of first comparator C om1, the outflow end ground connection of first current source I, the anode of first comparator is connected with the anode of second comparator, jointly meets comparative voltage Vcm; When the output of first comparator C om1 is high, output time is TH, or the output of first comparator C om1 while being low output time be TL;

A termination analog input Vref of second sampling switch Sh, one end of another termination reference sample capacitor C ref and one end of second discharge switch Sd, the other end ground connection of reference sample capacitor C ref; The inflow end of second current source I of another termination of second discharge switch Sd and the negative terminal of second comparator C om2, the outflow end ground connection of second current source I, the output Com2 of second comparator is output reference time TR.

Wide input range linear voltage time translation method is realized by means of aforementioned transducer, comprises the steps: that two sampling switch Sh closures are sampled two groups of analog voltage signals of input by sampling capacitance CH or CL and Cref.Then sampling switch Sh disconnects, discharge switch Sd closure, thus the electric discharge to sampling capacitance in special time completed, and comparator C om1 and Com2 compare by Detection capacitance both end voltage and with comparison signal, thereby realize pulse output, complete the conversion of analog voltage to time signal.

The utility model possesses following technique effect:

The utility model provides a kind of wide input range linear voltage time converter, compared with tradition time VTC, the VTC proposing does not rely on the transmission characteristic of device, but adopting the charge and discharge mode of electric capacity-comparator to realize voltage to the conversion of time, this working method has the feature of larger input range and the good linearity.Foregoing circuit and concrete implementation method, realized the conversion to time signal to input analog voltage signal, met the needs in practical application.

Accompanying drawing explanation

Fig. 1 is the wide input range linear voltage time converting circuit principle schematic that the utility model provides;

Fig. 2 is the wide input range linear voltage time converting circuit sequential chart that the utility model provides;

In accompanying drawing, the list of parts of each label representative is as follows:

VH: high input voltage; VL: low input;

Vref: input reference voltage; Vcm: comparative voltage;

I: current source; Sh: sampling switch; Sd: discharge switch;

CH (L): high/low input voltage sampling capacitance; Cref: input reference voltage sampling capacitance;

Com1: comparator 1; Com2: comparator 2;

TH (L): high/low output time; TR: output reference time.

Embodiment

In order to increase the input range of traditional VTC, make output in a big way, keep linear, the utility model provides a kind of time amplifier circuit, described below:

The circuit structure of wide input range linear voltage time converter (VTC) is referring to figure mono-, realizing circuit comprises: two sampling switch Sh, two discharge switch Sd, two sampling capacitance CH (L) and Cref, two current source I and two comparator C om1 and Com2.

A termination analog input VH(L of first sampling switch Sh), one end of one end of another termination sampling capacitance CH (L) and first discharge switch Sd.The other end ground connection of sampling capacitance CH (L).The inflow end of first current source of another termination I of first discharge switch Sd and the negative terminal of first comparator C om1.The outflow end ground connection of first current source I.The anode of first comparator is connected with the anode of second comparator, jointly meets comparative voltage Vcm.The output of first comparator C om1 is high (low) output time TH (L).

A termination analog input Vref of second sampling switch Sh, one end of another termination reference sample capacitor C ref and one end of second discharge switch Sd.The other end ground connection of reference sample capacitor C ref.The inflow end of second current source I of another termination of second discharge switch Sd and the negative terminal of second comparator C om2.The outflow end ground connection of second current source I.The output Com2 of second comparator is output reference time TR.

Two sampling switch Sh closures are sampled two groups of analog voltage signals of input by sampling capacitance CH (L) and Cref.Then sampling switch Sh disconnects, discharge switch Sd closure, thus the electric discharge to sampling capacitance in special time completed, and comparator C om1 and Com2 compare by Detection capacitance both end voltage and with comparison signal, thereby realize pulse output, complete the conversion of analog voltage to time signal.

For making the purpose of this utility model, technical scheme and advantage clearer, below in conjunction with accompanying drawing, the utility model execution mode is described in further detail.

Describe to scheme a pair of this figure method of work, described below:

Figure mono-has shown the wide input range linear voltage time converter structure proposing.What figure bis-showed is its corresponding sequential chart.To simplify the analysis, ignore gate delays at different levels.As shown in Figure 2, in the starting stage, sampling switch Sh closure, discharge switch Sd disconnects.Sampling capacitance CH(L) and Cref at sampled voltage VH(or VL) and Vref under charge, in the time that sampled voltage is the VH higher than Vref, sampling capacitance is charged to VH, in the time that sampled voltage is the VL lower than Vref, sampling capacitance is charged to VL.In the t0 moment, two sampling switch Sb disconnect, and two discharge switch Sd are simultaneously closed.At this moment sampling capacitance CH(L) and Cref on voltage start to reduce take the time as function linearity.As sampling capacitance CH(L) and Cref on voltage during lower than the threshold voltage of comparator C om1 and Com2, the output of two comparators is overturn.Suppose that current source I is identical, TR and TH(or TL so) between time difference just and the poor VH(of input voltage or VL) and Vref linear correlation.

In the time that input voltage is VL, its magnitude of voltage is lower than Vref, and the discharge time of Vref and VL, difference was:

${\mathrm{\ΔT}}_1=\frac{C}{I}(V_{\mathrm{ref}}-\mathrm{VL})$

In like manner, in the time that input voltage is VH, its magnitude of voltage is higher than Vref, and the discharge time of VH and Vref, difference was:

${\mathrm{\ΔT}}_2=\frac{C}{I}(\mathrm{VH}-V_{\mathrm{ref}})$

Time difference TH-TL is the conversion range of time converter.Input voltage range is VH-VL, and time difference is proportional.Select suitable current source I and capacitance C, the linear session transducer of proposition can obtain larger linear input range than traditional voltage time transducer.

Take a kind of wide input range linear voltage time converter as example, analyze its operation principle below, described below:

Suppose that adopting following V parameter DD is 1.8V, VSS is 0V, and C is 150fF, and I is 10 μ A, and Vcm is 0.6V, and VL is 0.9V, and VH is 1.5V, and VR is 1.2V.In the starting stage, sampling capacitance completes the sampling to input analog voltage.If the analog voltage of input is VH and Vref, in the time of t0=5ns, two groups of sampling capacitances start electric discharge.In the time of t3=22.5ns and t2=18ns, two groups of comparators overturn, output TH and TR, and the poor TH-TR of output time and voltage difference VH-Vref are linear.If the analog voltage of input is Vref and VL, in the time of t0=5ns, two groups of sampling capacitances start electric discharge.In the time of t2=18ns and t1=13.5ns, two groups of comparators overturn, output TH and TR, and the poor TH-TR of output time and voltage difference VH-Vref are linear.Thereby complete the conversion of input voltage signal to time signal.Tens millivolts of the input voltages of conventional voltage time converter, change-over time hundreds of psec, the input voltage range of the voltage time transducer of proposition can reach 0.6V, can reach nanosecond change-over time, compares traditional converter performance and improve a lot.

Claims (1)

1. a wide input range linear voltage time converter, is characterized in that, comprising: two sampling switch Sh, and two discharge switch Sd, two sampling capacitance CH or CL and Cref, H wherein represents high, L represents low; Two current source I and two comparator C om1 and Com2;

Termination analog input VH or a VL of first sampling switch Sh, one end of one end of another termination sampling capacitance CH or CL and first discharge switch Sd, the other end ground connection of sampling capacitance CH or CL, the inflow end of first current source of another termination I of first discharge switch Sd and the negative terminal of first comparator C om1, the outflow end ground connection of first current source I, the anode of first comparator is connected with the anode of second comparator, jointly meets comparative voltage Vcm; When the output of first comparator C om1 is high, output time is TH, or the output of first comparator C om1 while being low output time be TL, front;

A termination analog input Vref of second sampling switch Sh, one end of another termination reference sample capacitor C ref and one end of second discharge switch Sd, the other end ground connection of reference sample capacitor C ref; The inflow end of second current source I of another termination of second discharge switch Sd and the negative terminal of second comparator C om2, the outflow end ground connection of second current source I, the output Com2 of second comparator is output reference time TR.

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