High linearity performance? Enhancement Mode Technology ? Low noise figure? Enhancement mode technology requires positive Vgs, thereby eliminating the need for the negative gate voltage associated with conventional depletion mode devices.
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High linearity performance? Enhancement Mode Technology ? Low noise figure? Enhancement mode technology requires positive Vgs, thereby eliminating the need for the negative gate voltage associated with conventional depletion mode devices. Note: Top View. Operation of this device in excess of any one of these parameters may cause permanent damage. Assumes DC quiescent conditions.
IGS at P1dB drive level is bias circuit dependent. See application section for additional information. Typical I-V Curves. Gain 2 GHz, 3 V, 60 mA. Distribution data sample size is samples taken from 9 different wafers. Future wafers allocated to this product may have nominal values anywhere between the upper and lower limits. Measurements made on production test board. This circuit represents a trade-off between an optimal noise match and a realizeable match based on production test equipment.
Circut losses have been de-embeaded from actual measurements. A mmho? Measurements obtained using production test board described in Figure 5. Typical values measured from a sample size of parts from 9 wafers. This circuit represents a trade-off between an optimal noise match and associated impedance matching circuit losses.
Circuit losses have been de-embedded from actual measurements. Fmin vs. Gain vs. OIP3 vs. P1dB vs. Figure Notes: 1. Idq represents the quiescent drain current without RF drive applied. Fmin values at 2 GHz and higher are based on measurements while the Fmins below 2 GHz have been extrapolated.
The Fmin values are based on a set of 16 noise figure measurements made at 16 different impedances using an ATN NP5 test system. From these measurements a true Fmin is calculated.
Refer to the noise parameter application section for more information. Fmin vs. Fmin dB 0. Fmin vs. Frequency and Ids at 3V. Note: 1. Gamma out is the reflection coefficient of the matching circuit presented to the output of the device. GHz 0. Frequency at 3V, 40 mA. S and noise parameters are measured on a microstrip line made on 0. The input reference plane is at the end of the gate lead. The output reference plane is at the end of the drain lead.
The parameters include the effect of four plated through via holes connecting source landing pads on top of the test carrier to the microstrip ground plane on the bottom side of the carrier. Two 0. Frequency at 3V, 60 mA. Frequency at 3V, 80 mA. Frequency at 4V, 60 mA. As opposed to a typical depletion mode PHEMT where the gate must be made negative with respect to the source for proper operation, an enhancement mode PHEMT requires that the gate be made more positive than the source for normal operation.
Therefore a negative power supply voltage is not required for an enhancement mode device. Instead of a 0. Matching Networks The techniques for impedance matching an enhancement mode device are very similar to those for matching a depletion mode device.
The only difference is in the method of supplying gate bias. S and Noise Parameters for various bias conditions are listed in this data sheet. The circuit shown in Figure 1 shows a typical LNA circuit normally used for and MHz applications Consult the Agilent Technologies website for application notes covering specific applications.
The high pass structure also provides low frequency gain reduction which can be beneficial from the standpoint of improving out-of-band rejection at lower frequencies. Capacitors C2 and C5 provide a low impedance in-band RF bypass for the matching networks. Resistors R3 and R4 provide a very important low frequency termination for the device. The resistive termination improves low frequency stability.
Their value should be chosen carefully as C3 and C6 also provide a termination for low frequency mixing products. These mixing products are as a result of two or more inband signals mixing and producing third order in-band distortion products. The low frequency or difference mixing products are bypassed by C3 and C6.
For best suppression of third order distortion products based on the CDMA 1. F in value. Smaller values of capacitance will not suppress the generation of the 1. Bias Networks One of the major advantages of the enhancement mode technology is that it allows the designer to be able to dc ground the source leads and then merely apply a positive voltage on the gate to set the desired amount of quiescent drain current Id.
Only when Vgs is increased above Vto, the device threshold voltage, will drain current start to flow. At a Vds of 3V and a nominal Vgs of 0.
The data sheet suggests a minimum and maximum Vgs over which the desired amount of drain current will be achieved. It is also important to note that if the gate terminal is left open circuited, the device will pull some amount of drain current due to leakage current creating a voltage differential between the gate and source terminals. The voltage for the divider is derived from the drain voltage which provides a form of voltage feedback through the use of R3 to help keep drain current constant.
Resistor R5 approximately 10k? Resistor R3 is calculated based on desired Vds, Ids and available power supply voltage. Vds is the device drain to source voltage. Ids is the desired drain current. Equation 2 calculates the value of resistor R3 which determines the drain current Ids.
Equation 3 calculates the voltage required at the junction of resistors R1 and R2. This voltage plus the step-up of the base emitter junction determines the regulated Vds.
Equations 4 and 5 are solved simultaneously to determine the value of resistors R1 and R2. R7 is chosen to be 1k?.
This resistor keeps a small amount of current flowing through Q2 to help maintain bias stability. R6 is chosen to be 10k?. This value of resistance is necessary to limit Q1 gate current in the presence of high RF drive level especially when Q1 is driven to P1dB gain compression point.
IBB was chosen to be 2 mA for this example. Active Biasing Active biasing provides a means of keeping the quiescent bias point constant over temperature and constant over lot to lot variations in device dc performance. The techniques of active biasing an enhancement mode device are very similar to those used to bias a bipolar junction transistor. Figure 2. An active bias scheme is shown in Figure 2. The constant voltage at the base of Q2 is raised by 0.
The constant emitter voltage plus the regulated VDD supply are present across resistor R3. Constant voltage across R3 provides a constant current supply for the drain current.
Resistors R1 and R2 are used to set the desired Vds. The combined series value of these resistors also sets the amount of extra current consumed by the bias network. The package model includes the effect of the pins but does not include the effect of the additional source inductance associated with grounding the source leads through the printed circuit board. The device S and Noise Parameters do include the effect of 0. When comparing simulation results between the measured S param- eters and the simulated nonlinear model, be sure to include the effect of the printed circuit board to get an accurate comparison.
This is shown schematically in Figure 3. More detailed application circuit information is available from Agilent Technologies. Consult the web page or your local Agilent Technologies sales representative.
Selection of transistor was relatively simple: due to accessibility, price and performance evaluation has won well-known ATF , which is possible to buy from many distributors. It turn me to the second issue, input reflections. So - we considered this LNA as fully debuged design. Well, based on the above consideration, I did not speculated more abt. As you may see from these pics, I really tried to do it as precise as possible.