- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄98008 > MAT03FHZ (ANALOG DEVICES INC) 20 mA, 36 V, 2 CHANNEL, PNP, Si, SMALL SIGNAL TRANSISTOR, TO-78 PDF資料下載
參數(shù)資料
| 型號(hào)： | MAT03FHZ |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 小信號(hào)晶體管 |
| 英文描述： | 20 mA, 36 V, 2 CHANNEL, PNP, Si, SMALL SIGNAL TRANSISTOR, TO-78 |
| 封裝： | METAL CAN-6 |
| 文件頁數(shù)： | 12/12頁 |
| 文件大小： | 575K |
| 代理商： | MAT03FHZ |
MAT03
–9–
REV. C
Q2 and Q3 are in series and operate at the same current levels so
the total output impedance is:
RO = hFE roQ3 @ (160)(1 M
) = 160 M.
Figure 5. Cascode Current Source
CURRENT MATCHING
The objective of current source or mirror design is generation of
currents that are either matched or must maintain a constant ra-
tio. However, mismatch of base emitter voltages cause output
current errors. Consider the example of Figure 5. If the resistors
and transistors are equal and the collector voltages are the same,
the collector currents will match precisely. Investigating the cur-
rent matching errors resulting from a nonzero VOS, we define
I
C as the current error between the two transistors.
Graph 6b describes the relationship of current matching errors
versus offset voltage for a specified average current IC. Note that
since the relative error between the currents is exponentially
proportional to the offset voltage, tight matching is required to
design high accuracy current sources. For example, if the offset
voltage is 5 mV at 100
A collector current, the current match-
ing error would be 20%. Additionally, temperature effects such
as offset drift (3
V/°C per mV of VOS) will degrade performance
if Q1 and Q2 are not well matched.
DIGITALLY PROGRAMMABLE BIPOLAR CURRENT
PUMP
The circuit of Figure 7 is a digitally programmable current
pump. The current pump incorporates a DAC08, and a fast
Wilson current source using the MAT03. Examining Figure 7,
the DAC08 is set for 2 mA full-scale range so that bipolar cur-
rent operation of
±2 mA is achieved. The Wilson current mirror
maintains linearity within the LSB range of the 8-bit DAC08
(
±2 mA/256 = 15.6 A resolution) as seen in Figure 8. A nega-
tive feedback path established by Q2 regulates the collector cur-
rent so that it matches the reference current programmed by the
DAC08.
Collector-emitter voltages across both Q1 and Q3 are matched
by D1, with Q3’s collector-emitter voltage remaining constant,
independent of the voltage across the current source output.
Since Q2 buffers Q3, both transistors in the MAT03, Q1 and Q3,
maintain the same collector current. D2 and D3 form a Baker
clamp which prevents Q2 from turning off, thereby improving
the switching speed of the current mirror. The feedback serves
to increase the output impedance and improves accuracy by re-
ducing the base-width modulation which occurs with varying
collector-emitter voltages. Accuracy and linearity performance
of the current pump is summarized in Figure 8.
Figure 6a. Current Matching Circuit
Figure 6b. Current Matching Accuracy %
vs. Offset Voltage
Figure 7. Digitally Programmable Bipolar Current Pump
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAT-03FH | 20 mA, 36 V, 2 CHANNEL, PNP, Si, SMALL SIGNAL TRANSISTOR, TO-78 |
| MAT-03EH | 20 mA, 36 V, 2 CHANNEL, PNP, Si, SMALL SIGNAL TRANSISTOR, TO-78 |
| MAT03GBC | 20 mA, 36 V, 2 CHANNEL, PNP, Si, SMALL SIGNAL TRANSISTOR, TO-78 |
| MAT04BIEY | 30 mA, 40 V, 4 CHANNEL, NPN, Si, SMALL SIGNAL TRANSISTOR |
| MAT04BY/883 | 30 mA, 40 V, 4 CHANNEL, NPN, Si, SMALL SIGNAL TRANSISTOR |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAT03GBC | 制造商:Analog Devices 功能描述: |
| MAT04 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Matched Monolithic Quad Transistor |
| MAT-04 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Matched Monolithic Quad Transistor |
| MAT-04A | 制造商:AD 制造商全稱:Analog Devices 功能描述:Matched Monolithic Quad Transistor |
| MAT04AY | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。