LNA for 23 cm band (based on MMIC SKY67151)

The prototype of new LNA was the previous design made on IC MGA633P8 two years ago. The HPF and LPF filters previously were made on LC components and then been replaced to LFCN-1200 and HFCN-1200 filters from Mini-Circuts.

LNA-23cm-SKY67151 schematic model
Fig. 1 LNA-23cm-SKY67151 schematic model

 

The project is a low noise amplifier range 23cm, made on the IC SKY67151 in the first stage. A distinctive feature of this LNA is MMIC and five dielectric resonators (BPF) between each stage. Also LNA has a high IP3 with very low value of NF.

The LNA designed in Microwave Office.

Expected Gain plot
Fig. 2.1 Expected Gain plot
Expected Noise figure plot
Fig. 2.2 Expected Noise figure plot
Expected Stability plot
Fig. 2.3 Expected Stability plot
Expected VSWR plot
Fig. 2.4 Expected VSWR plot

The input VSWR is less than 1.5 and not achievable with the transistors in input stage. The chip contains embedded matching circuit which allows the smaller values of input VSWR. LNA is absolutely stable in the entire frequency range of the filter. BW at -3 dB equals 120MHz. The attenuation outside the passband is better than 40dB. Applying a filter of order 5 which coupled with high linearity LNA allows use in strong signals environment and other sources of RF interference.

The RF input power of 21dBm allows use the LNA with antenna relay which have very small separation between RX/TX ports in case of QRO. For low power transistors in other LNAs that power is rarely more than 5dBm.

The very low noise figure (NF < 0.3 dB) makes this LNA attractive for EME QSO. For convenience of use with different types of antenna relays there are available options with SMA and N-type input and output connectors. OIP3 LNA equals 37dBm.

Amplifier is built on SKY67151 and SPF5189 chips. The input matching circuit is designed to achieve the minimum NF with low ESR and high Q capacitors. The inductance is designed as a microstrip line and has the minimum loss (compared to SMD) which has a beneficial effect on the overall noise factor of the whole amplifier. Low-noise voltage regulator 6 Volt made on IC LP3878. Inductances in the power supply circuit are MPL. Power supply (+ 8V to +12V) of LNA can be fed through the cable or separate wire. There is also a protection against reverse polarity power supply.

Schematic circuit of LNA is shown on Fig. 3.1

LNA-23cm-SKY67151 schematic circuit
Fig. 3.1 LNA-23cm-SKY67151 schematic circuit (archive design)

Actual edition of two-cascade LNA, G = 33 dB, with MSL filter Fig. 3.2 (update from 2017-07-12)

Two-cascades LNA 23cm with MSL filter
Fig. 3.2 Two-cascades LNA 23cm with MSL filter (update from 2017-07-12)

Actual edition of one-cascade LNA, G = 20 dB, with MSL filter Fig. 3.3 (current edition)

One-cascade LNA 23cm with MSL filter
Fig. 3.3 One-cascade LNA 23cm with MSL filter (update from 2017-07-12)

The board size is 61 x 32 mm (FR4 material 1 mm with metallized holes, previous edition)

LNA 23cm ceramic filter edition
Fig. 4.1 LNA 23cm ceramic filter edition (previous edition)
Two-cascades LNA 23cm with MSL filter
Fig. 4.2 Two-cascades LNA 23cm with MSL filter (previous edition)

Actual edition of two-cascade LNA, SAW filter Fig. 4.3

Project update from 2018-12-14, layout, SAW filter
Fig 4.3 Project update from 2018-12-14, layout, SAW filter

Actual edition of one-cascade LNA, G = 20 dB, with MSL filter Fig. 4.4 (current edition)

One-cascade LNA 23cm with MSL filter
Fig. 4.4 One-cascade LNA 23cm with MSL filter (current edition)

The housing is made following the microwave requirements by milling aluminum and coated with a composition for soldering.

Project update from 2018-12-14, SAW filter
Fig. 5.1 Project update from 2018-12-14, SAW filter

The graph of the noise figure (NF) is shown in Pic. 6

NF of LNA
Pic. 6 NF of LNA

LNA 21cm

LNA 21cm N-female
LNA 21cm N-female
LNA 21cm SMA-female
LNA 21cm SMA-female
LNA 21cm layout
LNA 21cm layout
LNA 21cm AFC
LNA 21cm AFC

Technical specifications of two-cascades LNA 23cm

  • Model: LNA-23cm-EME
  • Based on: SKY67151 (1st cascade) and PGA-103+ (2nd cascade)
  • Gain: > 34 dB
  • Noise figure: < 0.3 dB at 1296 MHz
  • OIP3: 37 dBm
  • Filter BW(-3 dB): < 100 MHz
  • P input: 21 dBm (max)
  • Supply operation: 8 — 12 V DC , IDQ = 150 mA
  • Inpedance: 50 ohms
  • RF connectors: N-female (by default) or SMA-female (by request)
  • Dimensions: 72 mm x 43 mm x 20 mm (w/o connectors)
  • Weight: 0.15 kg

The package contains

  • 1 x LNA-23cm-EME

Technical specifications of one cascade LNA 23cm

  • Model: LNA-23cm-EME-1st
  • Based on: SKY67151
  • Gain: > 20 dB
  • Noise figure: < 0.3 dB at 1296 MHz
  • OIP3: 37 dBm
  • Filter BW(-3 dB): < 100 MHz
  • P input: 21 dBm (max)
  • Supply operation: 8 — 12 V DC , IDQ = 90 mA
  • Inpedance: 50 ohms
  • RF connectors: N-female (by default) or SMA-female (by request)
  • Dimensions: 72 mm x 43 mm x 20 mm (w/o connectors)
  • Weight: 0.15 kg

The package contains

  • 1 x LNA-23cm-EME-1st

You can order this LNAs via e-mail: e-mail logo sales@vhfdesign.com or by filling out this form.

Appearance

LNA 23cm EME
Fig. 6.4 LNA 23cm EME, one cascade edition, SMA-female, assembly from 2017-10-01
LNA 23cm EME
Fig. 6.4 LNA 23cm EME, one cascade edition, N-female, assembly from 2017-10-01
LNA 23cm EME
Fig. 6.3 LNA 23cm EME, two cascades edition, N-female, assembly from 2017-10-01
LNA-23cm-N-female in housing
Pic. 6.1 LNA-23cm-N-female in housing
LNA-23cm-SMA-female in housing
Pic. 6.4 LNA-23cm-SMA-female in housing

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