Datasheet MRF151G Datasheet (Motorola)

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Page 1

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SEMICONDUCTOR TECHNICAL DATA

The RF MOSFET Line

   

N–Channel Enhancement–Mode MOSFET

Designed for broadband commercial and military applications at frequencies to 175 MHz. The high power, high gain and broadband performance of this device makes possible solid state transmitters for FM broadcast or TV channel frequency bands.

• Guaranteed Performance at 175 MHz, 50 V:

Output Power — 300 W Gain — 14 dB (16 dB Typ) Efficiency — 50%

• Low Thermal Resistance — 0.35°C/W

• Ruggedness Tested at Rated Output Power

• Nitride Passivated Die for Enhanced Reliability

Order this document

by MRF151G/D



300 W, 50 V, 175 MHz

N–CHANNEL

BROADBAND

RF POWER MOSFET

G G

(FLANGE)

CASE 375–04, STYLE 2

MAXIMUM RATINGS

Rating Symbol Value Unit

Drain–Source Voltage V Drain–Gate Voltage V Gate–Source Voltage V Drain Current — Continuous I Total Device Dissipation @ TC = 25°C

Derate above 25°C Storage Temperature Range T Operating Junction Temperature T

DSS

DGO

stg

125 Vdc 125 Vdc ±40 Vdc

40 Adc

500

2.85

–65 to +150 °C

200 °C

THERMAL CHARACTERISTICS

Characteristic Symbol Max Unit

Thermal Resistance, Junction to Case R

NOTE — CAUTION — MOS devices are susceptible to damage from electrostatic charge. Reasonable precautions in handling and packaging MOS devices should be observed.

θJC

0.35 °C/W

Watts

W/°C

REV 8

 Motorola, Inc. 1997

MRF151GMOTOROLA RF DEVICE DATA

Page 2

ELECTRICAL CHARACTERISTICS (T

Characteristic Symbol Min Typ Max Unit

= 25°C unless otherwise noted.)

OFF CHARACTERISTICS (Each Side)

Drain–Source Breakdown Voltage (VGS = 0, ID = 100 mA) V Zero Gate Voltage Drain Current (VDS = 50 V, VGS = 0) I Gate–Body Leakage Current (VGS = 20 V, VDS = 0) I

ON CHARACTERISTICS (Each Side)

Gate Threshold Voltage (VDS = 10 V, ID = 100 mA) V Drain–Source On–Voltage (VGS = 10 V, ID = 10 A) V Forward Transconductance (VDS = 10 V, ID = 5.0 A) g

DYNAMIC CHARACTERISTICS (Each Side)

Input Capacitance (VDS = 50 V, VGS = 0, f = 1.0 MHz) C Output Capacitance (VDS = 50 V, VGS = 0, f = 1.0 MHz) C Reverse Transfer Capacitance (VDS = 50 V, VGS = 0, f = 1.0 MHz) C

FUNCTIONAL TESTS

Common Source Amplifier Power Gain

(VDD = 50 V, P Drain Efficiency

(VDD = 50 V, P Load Mismatch

(VDD = 50 V, P

VSWR 5:1 at all Phase Angles)

= 300 W, IDQ = 500 mA, f = 175 MHz)

out

= 300 W, f = 175 MHz, ID (Max) = 11 A)

out

= 300 W, IDQ = 500 mA,

out

(BR)DSS

DSS GSS

GS(th)

DS(on)

iss

oss

rss

η 50 55 — %

125 — — Vdc

— — 5.0 mAdc — — 1.0 µAdc

1.0 3.0 5.0 Vdc

5.0 7.0 — mhos

— 350 — pF — 220 — pF — 15 — pF

14 16 — dB

No Degradation in Output Power

C5C4

BIAS 0–6 V

–

INPUT

R1 — 100 Ohms, 1/2 W R2 — 1.0 kOhm, 1/2 W C1 — Arco 424 C2 — Arco 404 C3, C4, C7, C8, C9 — 1000 pF Chip C5, C10 — 0.1 µF Chip C6 — 330 pF Chip C11 — 0.47 µF Ceramic Chip, Kemet 1215 or

C11 — Equivalent (100 V)

C12 — Arco 422 L1 — 10 Turns AWG #18 Enameled Wire,

L1 — Close Wound, 1/4″ I.D.

L2 — Ferrite Beads of Suitable Material for

L2 — 1.5–2.0 µH Total Inductance

Unless Otherwise Noted, All Chip Capacitors are ATC Type 100 or Equivalent.

Figure 1. 175 MHz Test Circuit

C10C9

D.U.T.

T1 — 9:1 RF Transformer. Can be made of 15–18 Ohms

T1 — Semirigid Co–Ax, 62–90 Mils O.D.

T2 — 1:4 RF Transformer. Can be made of 16–18 Ohms

T2 — Semirigid Co–Ax, 70–90 Mils O.D.

Board Material — 0.062″ Fiberglass (G10), 1 oz. Copper Clad, 2 Sides, εr = 5.0

NOTE: For stability, the input transformer T1 must be loaded

NOTE: with ferrite toroids or beads to increase the common

NOTE: mode inductance. For operation below 100 MHz. The

NOTE: same is required for the output transformer.

See Figure 6 for construction details of T1 and T2.

C7 C8

C11

C12

50 V

–

OUTPUT

MRF151G 2

MOTOROLA RF DEVICE DATA

Page 3

TYPICAL CHARACTERISTICS

1000

500

200

100

C, CAPACITANCE (pF)

0 1020304050

VDS, DRAIN–SOURCE VOLTAGE (VOL TS)

iss

oss

rss

Figure 2. Capacitance versus

Drain–Source Voltage*

*Data shown applies to each half of MRF151G.

1.04

1.03

1.02

1.01 1

0.99

0.98

0.97

0.96

0.95

0.94

0.93

0.92

, DRAIN-SOURCE VOLTAGE (NORMALIZED)

0.91

0.9

–25 0 25 50 75 100

TC, CASE TEMPERATURE (

250 mA

100 mA

ID = 5 A

4 A

2 A

1 A

2000

VDS = 30 V

1000

, UNITY GAIN FREQUENCY (MHz)

048121620

2 6 10 14 18

, DRAIN CURRENT (AMPS)

15 V

Figure 3. Common Source Unity Gain Frequency

versus Drain Current*

100

TC = 25°C

, DRAIN CURRENT (AMPS)

2 20 200

VDS, DRAIN–TO–SOURCE VOL TAGE (VOL TS)

Figure 4. Gate–Source V oltage versus

Case T emperature*

HIGH IMPEDANCE

WINDINGS

CENTER

TAP

IMPEDANCE

Figure 6. RF Transformer

4:1

RATIO

Figure 5. DC Safe Operating Area

9:1

IMPEDANCE

RATIO

CONNECTIONS

TO LOW IMPEDANCE

WINDINGS

MRF151GMOTOROLA RF DEVICE DATA

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TYPICAL CHARACTERISTICS

350

f = 150 MHz

300

250

200

150

, OUTPUT POWER (WATTS)

100

out

0510

, INPUT POWER (WATTS)

VDD = 50 V IDQ = 2 x 250 mA

175 MHz

200 MHz

, POWER GAIN (dB)

VDD = 50 V

IDQ = 2 x 250 mA

= 150 W

out

2 5 10 30 100 200

Figure 7. Output Power versus Input Power Figure 8. Power Gain versus Frequency

f, FREQUENCY (MHz)

f = 175 MHz

150

125

INPUT, Z

150

125

f = 175 MHz

OUTPUT, ZOL*

(DRAIN TO DRAIN)

ZOL* = Conjugate of the optimum load impedance

ZOL* = into which the device output operates at a ZOL* = given output power, voltage and frequency.

Zo = 10

Ω

100

(GATE TO GATE)

100 30

Figure 9. Input and Output Impedance

MRF151G 4

MOTOROLA RF DEVICE DATA

Page 5

RF POWER MOSFET CONSIDERA TIONS

MOSFET CAPACITANCES

The physical structure of a MOSFET results in capacitors between the terminals. The metal anode gate structure determines the capacitors from gate–to–drain (Cgd), and gate– to–source (Cgs). The PN junction formed during the fabrication of the RF MOSFET results in a junction capacitance from drain–to–source (Cds).

These capacitances are characterized as input (C put (C

) and reverse transfer (C

oss

) capacitances on data

rss

iss

), out-

sheets. The relationships between the inter–terminal capacitances and those given on data sheets are shown below. The C

can be specified in two ways:

iss

1. Drain shorted to source and positive voltage at the gate.

2. Positive voltage of the drain in respect to source and zero volts at the gate. In the latter case the numbers are lower. However, neither method represents the actual operating conditions in RF applications.

DRAIN

SOURCE

iss

oss

rss

= Cgd = C

= C

GATE

LINEARITY AND GAIN CHARACTERISTICS

In addition to the typical IMD and power gain data presented, Figure 3 may give the designer additional information on the capabilities of this device. The graph represents the small signal unity current gain frequency at a given drain current level. This is equivalent to fT for bipolar transistors. Since this test is performed at a fast sweep speed, heating of the device does not occur. Thus, in normal use, the higher temperatures may degrade these characteristics to some extent.

DRAIN CHARACTERISTICS

One figure of merit for a FET is its static resistance in the full–on condition. This on–resistance, V

DS(on)

, occurs in the linear region of the output characteristic and is specified under specific test conditions for gate–source voltage and drain current. For MOSFETs, V

has a positive temperature

DS(on)

coefficient and constitutes an important design consideration at high temperatures, because it contributes to the power dissipation within the device.

GATE CHARACTERISTICS

The gate of the MOSFET is a polysilicon material, and is electrically isolated from the source by a layer of oxide. The input resistance is very high — on the order of 109 ohms — resulting in a leakage current of a few nanoamperes.

Gate control is achieved by applying a positive voltage slightly in excess of the gate–to–source threshold voltage, V

GS(th)

Gate Voltage Rating — Never exceed the gate voltage rating. Exceeding the rated VGS can result in permanent damage to the oxide layer in the gate region.

Gate Termination — The gates of these devices are essentially capacitors. Circuits that leave the gate open–cir-

cuited or floating should be avoided. These conditions can result in turn–on of the devices due to voltage build–up on the input capacitor due to leakage currents or pickup.

Gate Protection — These devices do not have an internal monolithic zener diode from gate–to–source. If gate protection is required, an external zener diode is recommended.

Using a resistor to keep the gate–to–source impedance low also helps damp transients and serves another important function. Voltage transients on the drain can be coupled to the gate through the parasitic gate–drain capacitance. If the gate–to–source impedance and the rate of voltage change on the drain are both high, then the signal coupled to the gate may be large enough to exceed the gate–threshold voltage and turn the device on.

HANDLING CONSIDERATIONS

When shipping, the devices should be transported only in antistatic bags or conductive foam. Upon removal from the packaging, careful handling procedures should be adhered to. Those handling the devices should wear grounding straps and devices not in the antistatic packaging should be kept in metal tote bins. MOSFETs should be handled by the case and not by the leads, and when testing the device, all leads should make good electrical contact before voltage is applied. As a final note, when placing the FET into the system it is designed for, soldering should be done with a grounded iron.

DESIGN CONSIDERATIONS

The MRF151G is an RF Power, MOS, N–channel enhancement mode field–effect transistor (FET) designed for HF and VHF power amplifier applications.

Motorola Application Note AN211A, FETs in Theory and Practice, is suggested reading for those not familiar with the construction and characteristics of FETs.

The major advantages of RF power MOSFETs include high gain, low noise, simple bias systems, relative immunity from thermal runaway, and the ability to withstand severely mismatched loads without suffering damage. Power output can be varied over a wide range with a low power dc control signal.

DC BIAS

The MRF151G is an enhancement mode FET and, therefore, does not conduct when drain voltage is applied. Drain current flows when a positive voltage is applied to the gate. RF power FETs require forward bias for optimum performance. The value of quiescent drain current (IDQ) is not critical for many applications. The MRF151G was characterized at IDQ = 250 mA, each side, which is the suggested minimum value of IDQ. For special applications such as linear amplification, IDQ may have to be selected to optimize the critical parameters.

The gate is a dc open circuit and draws no current. Therefore, the gate bias circuit may be just a simple resistive divider network. Some applications may require a more elaborate bias sytem.

GAIN CONTROL

Power output of the MRF151G may be controlled from its rated value down to zero (negative gain) by varying the dc gate voltage. This feature facilitates the design of manual gain control, AGC/ALC and modulation systems.

MRF151GMOTOROLA RF DEVICE DATA

Page 6

P ACKAGE DIMENSIONS

U G

–A–

RADIUS 2 PL

0.25 (0.010) B

–B–

–T–

CASE 375–04

ISSUE D

SEATING PLANE

NOTES:

1. DIMENSIONING AND TOLERANCING PER ANSI

Y14.5M, 1982.

2. CONTROLLING DIMENSION: INCH.

STYLE 2:

PIN 1. DRAIN

2. DRAIN

3. GATE

4. GATE

5. SOURCE

MILLIMETERSINCHES

DIM MIN MAX MIN MAX

A 1.330 1.350 33.79 34.29 B 0.370 0.410 9.40 10.41 C 0.190 0.230 4.83 5.84 D 0.215 0.235 5.47 5.96 E 0.050 0.070 1.27 1.77 G 0.430 0.440 10.92 1 1.18 H 0.102 0.112 2.59 2.84 J 0.004 0.006 0.1 1 0.15 K 0.185 0.215 4.83 5.33 N 0.845 0.875 21.46 22.23 Q 0.060 0.070 1.52 1.78 R 0.390 0.410 9.91 10.41 U 1.100 BSC 27.94 BSC

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MRF151G 6

◊

MOTOROLA RF DEVICE DATA

*MRF151G/D*

MRF151G/D